How to test your YouTube thumbnail
- Add your thumbnail. Pick it, drop it or paste it. Add up to three versions to compare. No picture at hand? Try the sample.
- Write the title. The counter shows YouTube’s 100-character limit, and each view cuts the title where YouTube does.
- Add your channel. Your channel name and photo, plus the views and the video’s length, make the preview look like the real thing.
- Look at every place. Home, Search, Up next, the phone and Compare, in light and dark mode. The shuffle button (“Move your video”) puts your video in another spot.
- Download. The thumbnail at 1280 × 720 as a JPG under 2 MB, ready to upload from a phone or a computer, or the preview as a PNG to share.
The other videos in the preview are made up, so you judge your thumbnail on its own, next to typical ones. Your pictures stay on your device.
Where your thumbnail shows
- Home: a grid of large thumbnails on a computer, with your channel photo and the title under each.
- Search: the biggest your thumbnail gets, with the start of your description next to it.
- Up next: a small thumbnail beside the video people are watching, where small details disappear.
- The YouTube app: the full width of a phone screen.
YouTube thumbnail size (2026)
| What | Requirement |
|---|---|
| Size | 3840 × 2160 px recommended (at least 640 px wide) |
| Shape | 16:9 |
| File | JPG or PNG, up to 50 MB from a computer (2 MB from the phone app) |
| Title | Up to 100 characters |
A thumbnail of another shape gets black bars. The download here is 1280 × 720 and under 2 MB, so it uploads from the phone app too.
What makes a thumbnail people click
- One clear subject. A face or one object, big, that still reads at the size of a stamp.
- Three words or fewer. The title already speaks; the picture adds what the title can’t.
- Strong contrast. Bright subject on a dark background, or the other way round. Test it in both light and dark mode.
- Nothing in the bottom-right corner. YouTube puts the video’s length there.
- Thumbnail and title work together. Don’t repeat the title in the picture: make people curious about what the title promises.
What the checks look at
- Size and shape: at least 640 px wide (bigger stays sharper; YouTube recommends 3840 × 2160), 16:9.
- The file: its weight against the 2 MB limit of YouTube’s phone app, and its type.
- The title: its length, and whether the end gets cut.
- Contrast and brightness: a flat, very dark or very bright picture blurs at small sizes or melts into the page.
- The corner: detail under the length badge.
Free, and what the app adds
The preview is free, with no account and no limit. aiCarousels turns your video into a carousel for LinkedIn and Instagram: the key points on slides, with a last slide that sends people to watch it.
