If you have used WordPress, then you have probably switched themes at least once in your life. If you haven’t, and this is your first time, then it is even better. The beauty of WordPress is that it makes it very easy for users to change themes. It is literally few clicks away. But changing themes is much more than simply clicking activate. In this article, we will provide you with a checklist of things that you MUST do before changing WordPress themes. These steps are critical to make sure the process goes smoothly otherwise you can end up losing elements that you did not mean to lose.
1. Take Notes on Your Current Theme
Many WordPress users surf the web to find solutions to their problems. Often they find those solutions in form of snippets that they add manually in their theme such as the functions.php or another file. Because these changes were made once, people have a tendency of not remembering them. Go through your theme files and note down all additional code that you added. You also want to check your current theme’s load time because this way you can compare the two. Go to a site like Pingdom Tools or use YSlow to test out different pages (Yes different pages, not just the homepage).
2. Be cautious of the Sidebars
You must make sure that your new theme is widget-ready. Sidebar widgets are really easy to use therefore a lot of users use it to customize it. We notice that sidebars are probably the most user-customized area of WordPress sites. People make tons of changes such as adding custom texts, images, links, advertisement, and other widgets. If you are using a widget-enabled theme, and you switch to a theme that is not widget-ready, then you will lose all of that. If you are using a widget-enabled WordPress theme, then this is not an issue.
Also anything that you modify in sidebar.php file of your old theme, will be overwritten. So make sure that you add those codes in the new theme sidebar.
3. Don’t lose tracking
Most bloggers use some sort of analytics whether it be Google Analytics, or one of the other services. A lot of us don’t use plugins to add the tracking codes. Some of us open the footer.php file and modify the codes. Some of our themes have a spot to place the adsense code. Whichever one is your case, you want to make sure that you copy and paste your tracking code to your new theme. This is one of the things that is very commonly overlooked by users. Because it is so simple, most of us forget about it.
4. The Good ‘ol RSS are you working?
A lot of us use FeedBurner for our WordPress RSS Feeds. One of the parts of integrating FeedBurner into WordPress is pointing your default feeds to FeedBurner this way you can have analytics on your feed subscribers. A lot of themes like Genesis, Standard Theme, and others allow you to integrate FeedBurner from their settings panel. You need to make sure that you keep the feed directed to FeedBurner otherwise there will be two RSS feeds for your blog. The main WordPress one, and the FeedBurner one which is taking the info from your WordPress RSS Feed. Except, you will lose count of a lot of the subscriber that you had because they were subscribed using the /feed/ url which no longer points to FeedBurner. Again, this does not mean you lose them, it just means that you can’t see them in the FeedBurner count.
5. Backup!!
You never have anything to lose by creating a backup. As a precautionary measure, you should backup all of your theme files, plugins, and the database. Although nothing should happen, but you can never be too safe. You can use BackupBuddy to create a full-site Backup for you.
6. Maintenance Mode
You probably don’t want your users to see while you are making the switch because they will end up seeing a broken site or such. It is best to turn on Maintenance mode for 15 – 20 minutes that it may take you to make sure that everything is working properly. Once you have setup Maintenance mode, you are good to go ahead and activate the new theme.
7. Testing all functionality and plugins
Once you have the new theme activated, you need to make sure that you retain all the functionality and plugins still work. Remember that good ol’ notes list that you created in step 1. This is the time where that can come handy. Go back and add any and all functionality that you want to bring from the old theme into the new theme if you haven’t done so already. Try out all the features including but not limited to the commenting process, single post pages, search, 404 page, archive page, contact page etc. Make sure all of your widgets are still there and are working.
On the plugin front, you just want to make sure that the formatting is still the same. A lot of plugins utilize your existing styles to display their output. So you probably want to make sure that they still look good with the new theme.
8. Cross Browser Compatibility
Test your site in all browsers you have access to. Browsers have a tendency of rendering things differently. Specially Internet Explorer. You want to make sure that your design looks good in major browsers. Some pretty looking themes have a tendency of breaking in various browsers. So if a lot of your audience is using Internet Explorer, then you want to make sure that it is still accessible to them.
9. Make those Third Party Items look pretty
If you are using Google Adsense or another ad company that allows you to format them, then your best bet is to customize them. For example, you previous site was orange, so you had orange links for Google Adsense. Now if it is blue, then you probably want to take that into account.
Same goes for twitter widget, facebook like buttons etc. Adjust those with your new color scheme. If you are going from a light to a dark design, or vice-versa, then you need to make those changes.
10. Let your Users Know
Turn off maintenance mode, and write a quick blog post to let the users know. Notice, you only spent like 15 – 20 minutes on checking things. There is no way that you could’ve catch all the bugs. By letting your users know, you can expect to get bug reports. We often ask our readers on twitter (@wpbeginner) for bug testing. Ask your audience via twitter, facebook etc to see if the site looks good in their browser. If they say YES, then its good news. If they say NO, then ask them to please take a screenshot of the issue. You can take a look at the issue and try to fix it. If you can’t fix it, then kindly ask the developer of the theme to fix it. Notice: unless you paid for the theme, these developers are NOT required to fix those issues for FREE.
People have all sort of browsers, screen resolutions, etc, so getting their opinion is important. Don’t forget to remind your RSS readers to visit the site as well, so they can see the goodies.
11. Pruning plugins
Themes are now coming pre-loaded with a lot of features. For example, if you are using Genesis or another theme that has BreadCrumbs, then you can get rid of Breadcrumb plugin of yours. The concept is simple. Get rid of things that you don’t need. One thing you should make sure though is often plugins can do the job better. For example a lot of themes are coming with tons of SEO features. Genesis, Thesis, Standard Theme, and all others boast their SEO features. We’d rather use a much more powerful plugin like WordPress SEO by Yoast. Make your choices wisely.
12. Take Baby Steps when Changing
You are working with a new theme here, so it is probably best that you make changes carefully. Change smaller elements to make sure that it behaves properly in all browsers. Then once you are comfortable enough, then you can make drastic changes. It’s important to learn the structure and semantics of the new theme before you make huge changes. This will allow you to detect the problem right away.
13. Test Loading Time
Take the load time numbers that you had on your old theme (from item 1 of this checklist), and compare the two. See what you can do to improve load time by checking out Syed’s presentation on Slideshare.
14. Monitor Bounce Rate
After switching themes, you want to make sure that you are monitoring bounce rate. Some themes are just more friendlier than others when it comes to navigating the readers around your site. If your bounce rate has increased compared to the previous theme, then you should probably work on that. Add related posts widgets, popular posts widgets, or simply have a better call-to-action for new readers.
15. Listen to your readers, and IMPROVE
When a new design comes out, users always have suggestions. They either love a specific feature, or hate a specific feature. Communicate with your audience using surveys or Facebook Polls. See what they would like to see improved, and then work on getting that done.
Do you have a checklist of your own when changing WordPress themes? Would love to hear it if we missed something.
I really got a lot out of this article on “what to do when changing themes” I didn’t know that themes cam with their own pages and that’s why I always had more pages than I needed.
That would depend on the theme, some have demo content that you have the choice to download or not.
i had been getting problem in accesing my wp dashboard….my cpanel is easily be able to access,but not the dashboard…
when i try to access it this shows
The page isn’t redirecting properly
An error occurred during a connection
try again
You may want to go through the recommendations in our article below:
https://www.wpbeginner.com/wp-tutorials/how-to-fix-error-too-many-redirects-issue-in-wordpress/
Thanks for the tips. This is great info.
You’re welcome, glad you found our guide helpful
Hi, my webpages appear blank even after editing pages and updating. I’ve tried deactivating all plugins and activating one by one but no improvement. What should i do? Should i change my theme?
You may want to try that, for other steps you can try you would want to take a look at our article here: https://www.wpbeginner.com/beginners-guide/beginners-guide-to-troubleshooting-wordpress-errors-step-by-step/
I’m using Google Analytics for WordPress by MonsterInsights plugin and have changed themes several times.
I’ve checked and Google Analytics tracking code still intact
This plugin also inserts tracking code for you when you install it
You normally will need to connect the plugin but yes, the plugin allows you to easily swap themes and keep your tracking information
Just wanted to say…AMAZING! What a fantasitc resource this site is. I am a complete novice with all this stuff, and you explain it clearly and in plain language that is easy to understand. I will be regularly visiting your site.
Thank you so much for helping so many strangers, like myself.
With gratitude
Julie
Thank you, glad our articles can be helpful
Hi
Thanks for the pos. However I have a problem about my theme
Google adsense is not showing on some pages and i don’t know the reason.
please could you review my site and tell me why this is happening, thanks
Google Adsense likely does not have a recommended ad for the page it’s not displaying on for the reason the ad is missing.
Hello,
I am a starter. When I changed the theme, all the sidebars like, home, shop, contact etc disappeared. But in the real theme model it is showing. What did I wrong
It would depend on your specific theme but normally you would want to check under Appearance>Widgets if it is content from the sidebar that is missing.
I have a WP site that I want to change. I’ve found a theme I like and want to download and start working on. My question is, if I download this theme is there a way I can work on it without disrupting the current site theme until I’m ready to make the new theme live? If not, what do I do? How/where can I set this theme up and add content without changing the current site?
If you preview the new theme under Appearance>Customize then as long as you don’t save you can see what your site would look like with that theme. If you wanted to set it up more in-depth, you could create a staging environment as we show in our article here:
https://www.wpbeginner.com/wp-tutorials/how-to-create-staging-environment-for-a-wordpress-site/
Hi Team,
I have an old non-responsive theme – and wish to migrate. My site Googles #1 in its’ space and I CANNOT lose that. Do I need to use the same permalinks / naming / structure? Can I obtain the info from my WP All in one SEO plugin and transfer? Do I need to add all the tags – cut n’ paste ect? Any advice would be helpful!
Mark
It would be best to keep your same permalinks but changing your theme shouldn’t affect those normally so it shouldn’t be an issue. IF you reach out to your SEO plugin they can let you know what SEO information they can transfer for you.
Hi author,
Great article.
Thanks for sharing the awesome piece of information.
You’re welcome
I was getting the 500 error message. Your advice on removing plugins and slowly adding them back was a great help. I have used those plugins for a long time but maybe they do not like my new theme. Thanks for the help.
Glad our recommendation was helpful
Very nice post
Thank you
i want to Make my site SEO how i can ? i dont know how to rank my website
For understanding SEO you would want to take a look at our page here: https://www.wpbeginner.com/wordpress-seo/
I am the webmaster/developer of many Department Sites built with Dreamweaver over many many years. On Site alone has over 300 web pages with over 7000 files/links (documents, media, images, etc). I’m retiring in 3 years and want to transition everything into another software where people in the various departments and section can update their own pages. I would like to get some idea how I should tackle this. I can’t use the same urls while developing because I’ll have to run parallel while developing.Wordpress replacements. Any advice would be appreciated
You could create a local installation for what it sounds like you’re looking for: https://www.wpbeginner.com/how-to-install-wordpress/#installlocal
An Awesome Content it really helped me out
Glad it helped
Hi
I m new, I create a WordPress blog and select a theme, in 2nd step I like to change theme and insert links into images. (Clickable image) when we click image, it will open new document.
1- Unfortunately, my themes not changed even after selection I click activate button. (Same old theme appear)
2- there is not option add link to image. (Create a clickable image) , I just add through HTML codes in thml mode but not working.
I need help in both problems. Thankd
1. Try clearing your caching to see if that is preventing you from seeing your changes.
2. When you select the image in the block editor, there is a Link Settings section where you can change where the image links to on click.
I find that WP Beginner is a great and useful site with lots of information, both for beginners as well as seasoned WP people on the net. A lot of work has gone into this site so Thank You for your efforts.
Hi John,
Thanks for the kind words.
Hi. I have a site up and running currently. I’d like to download a new theme and play with it/build it out while my other site is still live. How do I go about this? I am looking and it appears I can download the new theme, but can I be working on it in the background while logged in and not effect the live site?
Hi MClay,
You can install a theme but as soon as you activate, it would become live on your site. The best way to test themes is to install them on a local server.
Hello everybody
Quick question: If I use the theme customizer on a specific theme but later change to another theme do I have to re-enter all the customizer settings for the new theme?
And secondly if i change back to the original theme when it still have the original customizer settings or will it have adopted the settings from the second theme?
thanks in advance…
Hi Lawrence,
Customizer settings are for a particular theme. If you switch theme then you will have to configure the new theme. If you switch back to the old theme, your settings will be there.
If we change anything in the site often our site traffic gets low?
I plan to upgrade from a free wordpress blog to an upgraded (premium) one in the future. At what point do you suggest making the switch? When you have 100 followers? 1000 views? Just whenever you’re ready? I don’t want to commit $8/month without knowing my blog is getting traffic.
Any advice appreached!
Thanks!
Hi Jenn,
We assume you are talking about WordPress.com. Please see our guide on the difference between self hosted WordPress.org vs free WordPress.com blog.
Hi,
As per my real experience (WordPress.com) , I suggest you to buy the premium plan (Maybe something like personal) because wordpress.com has really very less features and modifications that you can make to make your Site look the best! To be honest , the first time I started with a premium plan of wordpress.com but ended up cancelling it and moving over to wordpress.org (It’s amazing!).
i have been asked to rebuild a wordpress website – i have content and SEO expertise but limited knowledge of any back end stuff. (i managed to muddle through building one wordpress site a few years ago using an avada theme) other than the domain name i am not looking to keep any of the content or structure from the existing site, so do i follow the steps to change the theme? or should i create a staging site in the same spot as the current site, build the new content there and then simply switch over when its ready for publishing? thinking of using avada theme again as it seems to rate well – i am building a small brochureware style of site.
Hi I love the info here and am a newbie so forgive me for what may seem like simple questions. I am currently running a .org site and want to switch to a new theme. I’ve uploaded the new theme but not activated it as I need to work on it before launching, the old theme info will not be transferred. (I own the domain) I believe I have to set up a sub directory in order to do this so it’s not seen until I’m ready…how??
Also will the new theme affect my current search results (do I have to copy any info to keep my status)
For my wp website, I am planning to upgrade from the free version of the theme to the pro version of the same theme. Currently I have plugins installed. Do I need to deactivate the plugins before upgrading to pro version & then reinstall?
Hi Surya,
Yes, you should. In case a plugin causes conflict with the theme you wouldn’t be able to find out which plugin. Disabling them will allow you to activate them one by one to see if they all work nicely with new theme.
I am preparing to move from WP.com to WP.org self hosted. I checked and I can keep my old theme on org but I would like to use a new premium theme going forward on the new site. Can you please advise what is the best way to go about it? I would also like to do a clean-up of my blog and refresh posts, delete posts that are no longer relevant and of course, revamp the look. Many thanks!
Hi Alex,
Please see our guide on properly switching WordPress themes.
I recently installed the flatsome theme in my WordPress/WooCommerce website. I’m trying to load products from my t-shirt fulfillment company but their POST requests are being ignored by my website like there’s nothing there. I’ve whitelisted all there IP addresses and give them the api key. They are unable to establish webhooks as well. Could this be a problem with the flatsome theme?
Hi Michael,
Please see our WordPress troubleshooting guide, it will help you figure out what’s causing the issue and how to fix it.
Very helpful! Thank you for providing this checklist. Excited to switch themes on my blog.
Hello!
From one perennial newbie to other newbies ….
Before I change ANYTHING on my WP site, I use the Export function under Tools in your dashboard – it is the fastest, accurate way of making sure you lose no content.
I save the xml file in a Documents folder on my hard drive. Then if you change a theme and it messes stuff up, then you import the xml file you saved on your hard drive back into the new WordPress theme.
I know there are all kinds of other ways but I challenge anyone that says that they are easier or cheaper. A standard XML file can be exported and imported so fast and saved so you do not lose your site. It only takes a few minutes and you do not have to pay for any of the expensive backup programs like Backup Buddy. Not saying Backup Buddy is bad, just expensive!
And maybe it is not for you if you are an amateur like me. I do my own sites. I do not do sites for others.
Good luck and happy exporting and importing!
-Charles Pedley
Hi Charles,
The method you described above works only for your posts, pages, and comments. It is not a full database backup. It can be used to import content only but it wouldn’t import any website settings stored in the database.
If price is your main concern, then you can try the free version of Updraft Plus. Also see our list of WordPress backup plugins for alternates.
Great article thanks. i have changed my theme several times 2017 to 2016 but now i am using Genesis and genesis sample child theme. i tried to change my header image but the code is not responsive. the image still stays the same. also when i tried to write a code in a text widget on the side bar it is not responsive. what could be wrong. thanks!
Hi Monika,
If you are editing code, then you need to make your changes in child theme. Theme frameworks use their own filters and functions that may sometimes override what you are trying to do in a child theme. See Genesis documentation for more help on customizing your child theme.
Hello…I have recently installed WP and upon instalation my website was replaced with a WP Theme “Twenty Seventeen” with all my contents gone. I attempted to undo everything to restore the original website and received a error message stating “Twenty Sixteen” directory not found. I uploaded the “Twenty Sixteen” theme but none of my original contents moved over. Please advise what I need to do to restore my original website.
Thanks
Hi Jimmy,
Did you install WordPress in a folder where another non-WordPress website was already installed? In that case, WordPress will overwrite your website. Your website files may still be there. Please ask your hosting provider, they may be able to provide you with a backup of your website or restore your website to an earlier state.
Thank you for your response! WordPress was installed in the same folder with a previous version of my website created via Word Press. I have spoke with my hosting company and they were not able to restore the website to a earlier version. We located the files and was advised to reinstall WP, which led to a response of “Twenty Sixteen” directory not found.
Jimmy, do you mean you installed ANOTHER version of WordPress? As far as I know you can only install 1 version of WordPress so you may have inadvertently overwritten all of the previous installed version of WordPress included content, theme etc and unless your hosting company can help restore from an old back up you are going to have to re-build from scratch. Have to admit, if your host does not have a back-up that is very odd and you should consider moving your hosting to a more responsible company.
I am getting ready to do a total redesign of a client’s website. I have backed it up and chosen a new WP theme but am not sure how to make the transition easy. Once you install a new theme, what do you do with the backed up version? Can you access it and copy and paste certain content back onto the new site?
Ex. They want to keep the bios of their directors but the current theme includes an element that allows you to add individual staff members info. It then creates a shortcode which you can add to any page on the site linking it to their bio. I will be using as the new theme but it doesn’t have a Staff feature. Any suggestions?
Hi Allison,
That’s one downside of using themes that rely on shortcodes or include functionality inside the theme instead of plugin. Your best option is to copy code blocks from their own theme, and try to add it into a site-specific WordPress plugin.
I am new to wordpress. So Can you please tell me whether changing the theme can cause data/content loss or broken href ?
Hi Ratul,
No, all your posts and comments are safely stored in your WordPress database.
Changing the theme will delete the plugins?
Hi Kishore,
No, it will not. However, if you are using a plugin that has some Theme Specific settings, then you may need to readjust those settings after switching the theme.
What happens to all your current url’s when you change your wordpress theme?
Do you keep them and and content?
Thanks
Hi Pete,
Yes, changing theme does not delete your content. However, it may change your site’s navigation menu which you can restore by visiting Appearance » Menus page.
You should NEVER directly edit theme files. If you do, then you will lose all your changes when you update the theme. Create a child-theme instead, and edit that. Then, when the underlying theme gets updated, you haven’t lost your changes.
Hi, how are you doing? Congratulation for your Blog. I really like it, and It always sold my problem. Keep going and thanks for creating this blog. Can you please help me or give me an idea. I’m gonna build a E commerce website that also have more feature than shopping. I bought a multi purpose eCommerce template and I customized it but not the CSS code but I put some new Icon, widget, and customize some new pages. I had to update my theme because it was not compatible with the woocommerce new version. I used a plugin called Easy Update theme & plugin cause I didn’t want to delete and upload the theme again. After I update the theme, the woocomerce plugin still not updated and the search bar missing on the front page it looks like the page deform. Do you have an idea where I can get a ecommerce multi purpose Child theme where I can just update it like I update all my plugin through WP . Where I dont have to delete my theme and uninstall my plugins and reinstall them again. I need a theme where I can get a serial number and update it automatically through WP. Thanks for anyone suggestion.
Please help +++ I bought a theme to try and revive my charity’s website look. It said nothing or no files would be changed or lost – not so. My front page with nice sliding picture disappeared and was deleted. I reverted back to my own theme but the front page was lost. I have another part of the site which is our US version. I want to copy its front page back to the UK version but on my admin side bar the tools tab is missing so I cannot import that page. I am desperate and have tried searching the web about tools missing without success.
my site is
the US version is
Please can you help me.. Thanks
Hi Tom,
When you buy a new theme, you should always test it out on a staging website or on local server. Once you got it setup, you can move it to the live site. Always backup your complete website before switching themes to stay safe.
Your previous theme may have a different setup process to add slider and other things. Go to your site’s US version and visit theme settings, or Appearance -> Customize page to see how it is setup. Then try to replicate them on your UK version.
Hope this helps.
Hi, when you say “Once you got it setup, you can move it to the live site”, how do you do this? Do you upload the theme as per normal and then the theme settings by exporting/importing a specific database table from the staging to the live site?
I didn’t even think of using a maintenance mode plugin until I came here. Thanks sooooooo much for that idea! This really helps out a lot because it makes the transition to a new website A LOT more professional. I’m not going to be able to finish the web redesign tonight, so this really comes in handy.
Hi Wpbeginner,
I have an issue with deleting wp default theme 2017.
My default theme in wp is 2017,when trying to remove it completely by clicking delete button(and install a new theme from elementor) failed!!!
Can you please help me to resolve the issue?
Being a non techie i dont want to touch and mess the existing settings unknowingly….a step by step guide will surely help ….
Radha
Hi Radha, that can happen if you don’t have a backup theme installed and 2017 is the only theme available. If you haven’t already tried it, try installing the new theme and activating it first, then trying to delete the 2017 theme and see if that helps.
But my advice would be to install and activate the new theme but leave 2017 theme there as a backup theme in case anything happens to your new theme.
Terry
How do I get my new posts on WordPress to be sent by email. To clarify, lets say I created a new post. I want the post to appear in my inbox. How do I handle this? Please advise.
Use IFTTT , they have a service that emails you new content in blogs.
Excellent. This is my second day with wordpress/themes. One suggestion for the old/new; Use notepad. Paste useful links such as:
https://www.wpbeginner.com/beginners-guide/checklist-15-things-you-must-do-before-changing-wordpress-themes/#respond
Into your notes and save a copy of what you did into your site folder.
Old school but effective.
thanks for such a useful article
cujstomer wants to change the hosting co… we keep the same domain….—
MY question: if i don’t transfer the whole site and later with the new hosting i choose another theme (or the same), how i am sure i will have all the images of my library i have now…? WP will have them or better copy / transfer to my external harddrive?…… — never did someething like this… is this a dumb question?
the site still under construction and small … no e-commerce….
thank you for any info you may provide….
BJ
Hi Beatrice
I would recommend downloading a full copy of your database before switching web host. And for safety I would transfer all media onto a hard drive.
Once you switch host, you can then upload the database to the new host server.
Mike
Thanks.
This was informative.
What about themes that claim AMP compatibility? We can’t just check the theme demo on AMP validator. Right?
switched to a broken theme and now I am locked out of the WP dashboard and my site. I have my site hosted on Amazon EC2. I don’t use Linux, just Windows machine. How can I can into my files? I am totally locked out and confused. Thank you.
Hey Juan,
You can use FTP or SSH to connect to your server and delete the theme that you installed.
Log into your hosting via cpanel. Delete the last themes folder you activated. WordPress will work behind to automatically exchange itself to default themes. Once you deleted it, try to log into your wordpress site. I hope this step will help you.
I’d like to hire a WordPress consultant who can take care of these maintenance issues for me, and maybe train me in some WordPress basics. Is there a preferred way to find one?
Hi Steve,
You can find freelance WordPress developers and consultants on websites like UpWok, Fiverr, etc.
Hey,
I’ve just switched my blog from WordPress.com to self hosted using bluehost. I imported all my posts from my .com account but now they are not formatting to my new theme.
My new theme is by mojo and has a post background box, but my old imported posts go outside this box border. Can any one help me to get my old posts to format properly to my new theme?
Thanks!
I am sorry I didn’t see this post until it was too late. My website is hosted on wp .org and while I was on the .com website I ruined my entire website in just a few short clicks. I didn’t realize they were connected.
I have been working to fix all the bugs created, but I still have one issue.
On my iPhone my website doesn’t seem to be responsive, the featured image is non existent and I see a bit of a boarder outside of the text, whereas before it filled the screen.
Do you have any suggestions for that?
Thank you for your time and attention on this, I really appreciate it.
Thanks a lot,
1 question – is there any way to observe / test the site with the new theme, before it goes live? something like a test environment, where the old theme is still in place but I can already “play and test” the new one?
Dan
Hi Dan,
You can install WordPress on your local computer. You can also just install a theme and then go to Appearance > Themes page. Click on the preview button below the theme you want to preview.
I zip up all my theme files and copy them into a subdirectory on my website, copy the database, use phpMyAdmin to change the site URLs to the subdirectory, set it for no search engines and test things there.
I have toyed with the idea of a local install but then you have to maintain the exact same versions of PHP, WordPress, MySQL etc to really have a proper testbed.
Here’s an article that’s good for showing how to migrate:
I am a new WordPress web developer and I am now using a couple of WordPress themes that I have changed back and forth between themes without really asking anyone HOW TO DO IT. I sometimes learn best this way . . by JUST DOING IT and making mistakes.
This is what I found . . .
1. The old theme or themes do NOT go away or get replaced with the NEW THEME UNTIL one refreshes using the “VIEW SITE” tab up top.
2. Take heed, I found that the NEW THEME was usually NOT what it looked like in the preview of all of the pretty and Free WordPress themes. Upgrade time!
3. I have kept initial coding changes minimal until I get to final theme. Just in case all gets wiped out.
4. I also have all site / page text backed up. So I can copy & paste if all gets wiped out from a theme change.
Hope this helps someone, even a little.
Happy New Year!