The dimensions take one line. What’s actually worth knowing is that you never see your thumbnail at the size you designed it, that the bottom-right corner belongs to YouTube, and that Shorts play by a different set of rules entirely.
The numbers
| Thing | Value | Note |
|---|---|---|
| Standard thumbnail | 1280 × 720, 16:9 | The universally safe upload size |
| Minimum width | 640 px | Works, but leaves no headroom for scaling |
| Format | JPG or PNG | PNG for flat graphics and hard-edged text; JPG for photographic |
| Shorts still | 1080 × 1920, 9:16 | Vertical — a different composition, not a crop |
| Duration badge | Bottom-right overlay | Treat that corner as unusable |
File-size limits and accepted formats do get adjusted, so if an upload is rejected, check YouTube’s own current help page rather than any article — including this one.
The two sizes that matter
You design at 1280 × 720 on a large monitor. Your viewer sees the image a couple of hundred pixels wide, in a column of competitors, on a phone. Every design decision should be made at the second size — which in practice means one subject, a headline of a few words, high contrast, and nothing small enough to require attention.
The corner you don’t own
The duration badge sits over the bottom-right of every standard thumbnail. Put your face, your logo or the last word of your headline there and it will be partially covered — not sometimes, always. It’s the single most common avoidable mistake in thumbnail composition, and it costs nothing to avoid: keep the bottom-right eighth clear.
Text on a YouTube thumbnail is a different job
This is where 16:9 diverges from vertical covers. On YouTube the title sits immediately next to the image, in full. Repeating it on the thumbnail wastes the only additional channel you have.
- Zero to four words. Often zero is right, if the image itself carries the idea.
- Say what the title doesn’t. If the title states the topic, the image text should supply the stake, the number, or the twist.
- Legible at 200 pixels wide. Which usually means larger than feels comfortable in your editor.
On Shorts, none of that applies: there’s often no visible title at all, so the still has to carry the entire pitch — two to five large words, as with an Instagram cover.
Shorts stills are not cropped thumbnails
A 16:9 thumbnail composed with the subject in the right third becomes, when cropped to vertical, a picture of someone’s shoulder. Vertical stills need to be composed vertically, and the same centre-square discipline that survives Instagram’s grid crop applies here — the full set of bands is in the safe zone guide.
Why thumbnails look blurry (it’s rarely resolution)
- Over-compression. A heavily-compressed JPG with hard-edged text picks up visible artefacts around the letterforms.
- Detail that can’t survive scaling. Thin strokes, small text and busy backgrounds all dissolve on the way down to browsing size.
- Upscaling a small source. A 640-wide image stretched to 1280 is soft before YouTube touches it.
The fix is nearly always fewer and larger elements rather than a bigger file.
Quick answers
What size should a YouTube thumbnail be?
1280 × 720 pixels, 16:9, as a JPG or PNG. That's a comfortable upload size — the image is displayed far smaller almost everywhere, so the resolution exists to survive scaling rather than to be seen at full size.
Where does the duration badge sit?
Bottom-right, overlaid on the thumbnail. Anything you place there — text, a face, a logo — competes with it. Treat the bottom-right corner as unusable and you'll never be surprised by it.
What size is a YouTube Shorts thumbnail?
Shorts are vertical, so the still is 9:16 at 1080 × 1920. It's shown in shelves and on your channel page as a tall tile, and the same centre-composition discipline that protects Instagram covers applies.
Why does my thumbnail look blurry?
Usually heavy compression rather than resolution: an over-compressed JPG, or fine detail and thin text that don't survive being scaled down to a couple of hundred pixels wide. Fewer, larger elements beats a higher-resolution file every time.
Make the 16:9 and the 9:16 from one video
Moonshot renders covers in 16:9, 9:16 and 1:1 from the same clip — composed for each shape rather than cropped from one another.
Open the thumbnail maker