A thumbnail that looks great full-screen in your editor can turn into an unreadable blur in a busy feed. This free tester shows your thumbnail the way viewers actually meet it — in a home feed, in search results, on a phone and in the tiny “up next” sidebar — in light and dark mode, next to other videos. Compare two versions side by side, check the technical requirements, and download a YouTube-ready file. Everything runs in your browser; your images are never uploaded.
Thumbnail tester
See your thumbnail the way viewers will — before you upload.
Home feed (desktop)
Search results
Phone
"Up next" sidebar — the smallest size
YouTube-ready = 1920 × 1080 JPG under 2 MB, which uploads from both the YouTube app and a computer. Your images are processed in your browser and never uploaded. The previews are a close imitation of a typical video feed, not the real site.
How to test your thumbnail
- Add your thumbnail as Thumbnail A. Want to compare? Add a second version as Thumbnail B.
- Type your real title, channel name and video length so the preview matches what viewers will see.
- Scroll through the previews. Switch to dark mode — lots of viewers browse that way — and click Shuffle position in feed to see your video between different neighbours.
- Fix what the checks flag, then click Download as YouTube-ready JPG for a 1920 × 1080 file under 2 MB.
What the checks mean
| Check | Why it matters |
|---|---|
| 16:9 shape | Video thumbnails are shown at 16:9. Other shapes get cropped or letter-boxed. |
| Resolution | Small images look soft on big screens and TVs. 1920 × 1080 or larger is a safe choice. |
| File size | The YouTube mobile app accepts thumbnails up to 2 MB; a computer accepts up to 50 MB. |
| Format | Thumbnails should be JPG or PNG. WebP files need converting first. |
| Bottom-right corner | The video length badge covers this corner, so text or a face placed there gets hidden. |
YouTube thumbnail size and requirements (2026)
| Requirement | Videos | Shorts |
|---|---|---|
| Recommended resolution | 3840 × 2160 | 2160 × 3840 |
| Minimum size | 640 pixels wide | 640 pixels tall |
| Aspect ratio | 16:9 | 9:16 |
| File formats | JPG or PNG | JPG or PNG |
| Maximum file size | 2 MB from the mobile app, 50 MB from a computer | 2 MB from the mobile app, 50 MB from a computer |
Source: YouTube Help, “Add video thumbnails” — checked October 2026. If you upload from your phone, keep files under 2 MB; the YouTube-ready download above does that for you while keeping 1920 × 1080 resolution.
Tips for thumbnails that get clicked
- Design for the smallest size first. If your thumbnail still works in the sidebar preview, it will work everywhere. Three to five big words is usually the maximum.
- Use strong contrast. Light text on a dark background (or the reverse) survives small sizes; mid-tones next to mid-tones disappear.
- Make faces big and expressive. A close-up reads at a glance; a full-body shot becomes a few pixels.
- Don’t repeat the title. The title sits right under the thumbnail — use the image to add curiosity or context instead.
- Check dark mode. Dark edges can melt into a dark feed. A subtle outline or brighter background helps your video stand out.
- Keep the bottom-right corner clear for the length badge.
Frequently asked questions
Is this thumbnail tester free?
Yes. There is no signup, no watermark and no limit on how many thumbnails you test.
Are my thumbnails uploaded anywhere?
No. The previews are built in your browser from your own files, which never leave your device.
Is this the real YouTube feed?
No — it is a close imitation of a typical video feed, built to show size, contrast and placement. Exact layouts vary slightly by device and change over time. Hub for Creators is not affiliated with YouTube.
What is the best YouTube thumbnail size?
YouTube recommends 3840 × 2160 for video thumbnails, with a 16:9 aspect ratio. 1920 × 1080 is a practical size that looks sharp and stays under the 2 MB limit for uploads from the mobile app.
Can I test Shorts thumbnails here?
This tester is built for regular 16:9 video thumbnails. For vertical 9:16 images, use the photo to 9:16 converter and check text placement with the Safe Zone Checker.
More free tools for creators
- Post Prep — resize, watermark and compress a whole batch, including YouTube thumbnail and banner sizes.
- Image to Vector — turn your channel logo into a sharp SVG.
- Safe Zone Checker — see what Shorts, Reels and TikTok cover on screen.
YouTube is a trademark of Google LLC. Hub for Creators is an independent project and is not affiliated with or endorsed by YouTube or Google.