A thumbnail has two jobs. It has to meet YouTube's technical requirements so it uploads and looks sharp. And it has to make sense in less than a second, at a size much smaller than the one you designed it at. The first job is a short list of numbers. The second is where most thumbnails fail. This guide covers both.
The official specs
According to YouTube Help, a custom thumbnail should be as large as possible and meet these guidelines:
| Videos | Shorts | |
|---|---|---|
| Aspect ratio | 16:9 | 9:16 |
| Recommended resolution | 3840 x 2160 | 2160 x 3840 |
| Minimum size | 640 pixels wide | 640 pixels high |
| Formats | Image formats such as JPG or PNG | Image formats such as JPG or PNG |
| File size, uploading from mobile | 2 MB | Not applicable (computer only) |
| File size, uploading from a computer | 50 MB | 50 MB |
Podcast playlists use a 1:1 ratio, and YouTube Help lists a 10 MB limit for podcast thumbnails on mobile.
A few points that cause trouble:
- You need a verified account. YouTube Help says you can upload your own thumbnail if your account is verified. Until then, you can only pick from the auto-generated options.
- Shorts thumbnails are computer-only for now. YouTube Help says custom Shorts thumbnails can currently only be added in YouTube Studio on a computer.
- The file limit depends on where you upload. A 10 MB PNG uploads from a computer but not from the mobile app. If you switch devices, a JPG under 2 MB is the safe choice.
- Policies apply to thumbnails too. YouTube's Community Guidelines and age-restriction rules cover custom thumbnails as well as videos.
What about 1280 x 720?
For years, 1280 x 720 was the standard size, and many templates still use it. It's still a valid 16:9 image, well above the 640-pixel minimum. YouTube Help now recommends larger images for sharper results on big screens. If you design at 1280 x 720, you're within the rules. If your tools and photos allow it, you can go larger.
Design for the size people actually see
You design a thumbnail full-screen. Viewers see it in a feed, often on a phone, often while scrolling. That's the size to design for.
A practical test: shrink your thumbnail to about 168 x 94 pixels and look at it next to a few others. That's a commonly used stand-in for a small mobile thumbnail, not an official YouTube number, but it's close enough to show what survives. You can do this by zooming out in your editor or by holding your phone at arm's length. Ask:
- Can you read every word without squinting?
- Can you tell what the picture shows?
- Is it clear what the video is about?
If any answer is no, the thumbnail needs simplifying. Making it bigger on your monitor won't fix it.
A checklist that works at small sizes
Use very few words
Every extra word makes every other word smaller. Keep text to a few words, and if a thumbnail needs a sentence to make sense, the idea is too complicated for a thumbnail. Put the detail in the title.
Put the topic word in the biggest text
Viewers decide quickly whether a video is for them. The biggest text should be the word that tells them what the video is about: the game, the dish, the tool, the problem. A clever line that doesn't name the topic makes people work to understand it, and most won't.
Make contrast obvious
Text needs to be very different in brightness from what's behind it. Color alone isn't enough: yellow on white, or red on dark brown, can look fine full-size and turn to mush at feed size. On a busy photo, add a thick outline, darken the photo or put a solid band behind the text.
Use a face, and make the eyes visible
If your video has a person in it, a clear face gives viewers something to read instantly: surprise, worry, delight. Crop close enough that the expression survives at feed size. Faces a long way from the camera become a few pixels.
Don't repeat the title
The title and thumbnail appear together. If they say the same thing, you've used two chances to make one point. Let the thumbnail show or add something the title doesn't say, and let the title carry the detail.
Keep the bottom right clear
YouTube places the video length in a small box in the bottom right corner of every thumbnail. Anything you put there gets covered.
Make it match the video
A thumbnail that promises something the video doesn't deliver can get a click, but viewers leave. YouTube's own A/B testing, below, measures watch time for exactly this reason.
Test it with Test & compare
YouTube Studio has a built-in A/B test. According to YouTube Help:
- You can test up to 3 titles, thumbnails, or title and thumbnail combinations on one video.
- It's available on a computer through YouTube Studio, and you need advanced features turned on.
- Shorts, scheduled live streams and Premieres can't be tested. Videos made for kids, set for mature audiences or set to private can't be tested either.
- The winner is the option with the highest watch time, not the highest click-through rate.
- Tests should finish within two weeks, sometimes sooner, depending on how many impressions the video gets.
- Results are Winner, Performed Same or Inconclusive. If a test is inconclusive, the first option you uploaded becomes the default.
- If any thumbnail in a test is below 720p, all of them are downscaled to 480p (854 x 480) for the test, so upload every option at 720p or more.
Make the options genuinely different, such as a different photo, a different main word or a different layout. Three versions with slightly different text colors rarely produce a clear result.
How our Thumbnail Maker helps
The Thumbnail Maker builds a 16:9 thumbnail in your browser. Your photo is never uploaded to our server.
- Pick a layout: text on the left, big centered text, or a photo on the right.
- Drag in your own photo, or use a plain color. Drag the preview to move the photo, and use zoom, fill or show-all to frame it. You can darken the photo to lift the text.
- Write your lines and set each one's size and color, plus outline width and color. Turn on a dark band behind the text for busy photos, and choose from nine text positions.
- Turn on the guide that shows where the video length appears, and you'll get a warning if text sits under it.
- Save as JPG, which is kept under 2 MB so it uploads from mobile or a computer, or as PNG, with a warning if the PNG goes over 2 MB.
- Fonts include Pretendard, Black Han Sans, Noto Sans JP and Inter, all under the SIL Open Font License.
- You can paste a video link to use its thumbnail as a background for practice. Other creators' thumbnails are protected by copyright, so use your own photos in your videos.
The limits:
- It saves at 1280 x 720. That meets YouTube's minimum and ratio, but it isn't the 3840 x 2160 YouTube Help now recommends.
- It makes 16:9 thumbnails only, not 9:16 Shorts thumbnails.
- It doesn't run A/B tests. Make your variants here, then test them with Test & compare in YouTube Studio.
Worth keeping in mind
- Specs get your thumbnail uploaded. The feed-size test decides whether it works.
- A JPG under 2 MB uploads from any device.
- Topic word big, few words, strong contrast, bottom right clear.
- Test & compare rewards watch time, so an honest thumbnail is also the one most likely to win.