Checked against the source
YouTube video thumbnail size
Short answer
YouTube Help recommends 3840 × 2160 pixels (16:9), at least 640 px wide, in JPG or PNG. The file limit is 50 MB from a computer and 2 MB from the mobile app, so a 4K JPG may be too large to upload from a phone.
Key takeaways
- The 2 MB mobile limit is the one that bites: in our tests a 3840 × 2160 JPG at quality 0.92 was between the sizes in the table below.
- A 1920 × 1080 thumbnail is a quarter of the pixels of 3840 × 2160, so its file is roughly a quarter of the size (computed).
- Podcast playlists use a 1:1 thumbnail instead of 16:9 (YouTube Help).
- Across our six test pictures the 3840 × 2160 result was 712 KB to 2.02 MB as a JPG at quality 0.92.
The size
| What | Value |
|---|---|
| Width | 3840 px |
| Height | 2160 px |
| Aspect ratio | 16:9 |
What the platform publishes
| What | Published value |
|---|---|
| Recommended | 3840 × 2160 px for videos (16:9); 2160 × 3840 px for Shorts (9:16) |
| Minimum | 640 px wide for videos; 640 px tall for Shorts |
| Formats | JPG or PNG |
| File size limit | 50 MB from a computer; 2 MB from the mobile app (10 MB for podcasts) |
| Podcast playlists | 1:1 instead of 16:9 |
Source: YouTube Help: Add custom thumbnails (checked 2026-10-05)
Resize it now
Scales and center-crops any image to exactly 3840 x 2160 px, in your browser. Nothing is uploaded, there is no file size cap and no daily limit.
Batch is unlimited and free - every image is processed on your device, so there is no queue and no daily cap.
What a 3840 × 2160 frame does to common photo shapes
The frame is 16:9. A photo of another shape is scaled until it covers the frame and the excess is cut from the center, which is what the resizer on this page does. This is computed from the shapes.
| Photo shape | Share of the photo kept | What is cut |
|---|---|---|
| 16:9 (1920 × 1080) | 100% | Nothing |
| 3:2 (3000 × 2000) | 84% | The top and bottom |
| 4:3 (4000 × 3000) | 75% | The top and bottom |
| 1:1 (2000 × 2000) | 56% | The top and bottom |
| 4:5 (1080 × 1350) | 45% | The top and bottom |
| 9:16 (1080 × 1920) | 32% | The top and bottom |
Computed.
Measured: six pictures through the resizer
The resizer on this page was run in headless Chromium on six test pictures (public domain NASA scans, a PNG graphic and two small pictures made from them): each is scaled to cover 3840 × 2160, drawn on a white background and saved as a JPG at quality 0.92. SSIM compares each result with a Lanczos crop of the same picture made by ffmpeg (1.0 would be identical); it is blank when the frame has an odd side, which ffmpeg's check cannot compare. Other browsers use their own encoders, so sizes can differ.
| Picture | Pixels | Scale | Result | Time | SSIM | Against the 2 MB mobile limit |
|---|---|---|---|---|---|---|
| Photo, nearly square | 3840 × 3877 | 1.00× | 2.02 MB | 127 ms | 0.94 | Over by 24.5 KB |
| Portrait | 2122 × 2644 | 1.81× (enlarged) | 1.02 MB | 99 ms | 0.97 | Under |
| Wide document scan | 3827 × 1588 | 1.36× (enlarged) | 1.46 MB | 107 ms | 0.96 | Under |
| Square PNG graphic | 5380 × 5432 | 0.71× | 1.49 MB | 111 ms | 0.92 | Under |
| Small portrait (1060 px) | 1060 × 1320 | 3.62× (enlarged) | 712 KB | 95 ms | 0.98 | Under |
| Small landscape (640 px) | 640 × 480 | 6.00× (enlarged) | 772 KB | 111 ms | 0.96 | Under |
A scale above 1 enlarges the picture to fill the frame; enlarging adds no detail, so start from a file at least as large as the frame. The limit used above is the 2 MB mobile limit.
Detail decides the file size (measured)
The same frame holds 8.29 megapixels whatever the picture, but the JPG size follows the detail in it. Bits per pixel is the file size in bits divided by the number of pixels in the frame.
| Picture | Result | Bits per pixel |
|---|---|---|
| Photo, nearly square | 2.02 MB | 1.95 |
| Portrait | 1.02 MB | 0.98 |
| Wide document scan | 1.46 MB | 1.40 |
| Square PNG graphic | 1.49 MB | 1.43 |
| Small portrait (1060 px) | 712 KB | 0.69 |
| Small landscape (640 px) | 772 KB | 0.74 |
Smooth areas and flat color compress to a fraction of what fine detail needs; a photograph full of texture is the expensive case. If a size limit matters, check your own picture, not an average.
Using the YouTube video thumbnail size
- Start from a file at least 3840 × 2160 pixels so nothing is enlarged.
- Keep faces, logos and text away from the edges; every crop above cuts the edges.
- Check the platform's own page before you rely on a figure; sizes change.
- The resizer above does the crop and the JPG in your browser; nothing is uploaded.
Frequently asked questions
What size is a YouTube thumbnail?
3840 × 2160 px at 16:9 is recommended; at least 640 px wide.
Why can't I upload my thumbnail from the app?
The mobile limit is 2 MB; a detailed 4K JPG is larger. Reduce the size or upload from a computer, where the limit is 50 MB.
How much of a 16:9 photo is kept in 3840 × 2160?
100% of its area (computed).
What is the aspect ratio of 3840 × 2160?
16:9, 8.29 megapixels.
How big will the file be?
Our six test pictures came out between 712 KB and 2.02 MB as JPGs at quality 0.92; detailed photographs are the large end.
Is my picture uploaded?
No. The resizer runs in your browser.
Other YouTube sizes
Sources
- YouTube Help: Add custom thumbnails (checked 2026-10-05)
- Wikimedia Commons: Buzz salutes the U.S. Flag (NASA, public domain), one of the test pictures (checked 2026-10-10)
- MDN: HTMLCanvasElement.toBlob() (JPEG quality) (checked 2026-10-10)
