YouTube recommends custom video thumbnails of 3840×2160 pixels at a 16:9 aspect ratio, with a minimum width of 640 pixels, uploaded as JPG or PNG. The file must be under 2 MB when uploaded from the mobile app and under 50 MB on desktop. A 1280×720 JPG under 2 MB works everywhere.
| Recommended size | 3840 × 2160 px |
|---|---|
| Minimum width | 640 px |
| Aspect ratio | 16:9 |
| Formats | JPG, PNG |
| Max file size (mobile app) | 2 MB |
| Max file size (desktop) | 50 MB |
| Safe choice for every upload | 1280 × 720 JPG, under 2 MB |
Source: YouTube Help · 2026-10-04
Which size should you use?
If you design in 4K, export 3840×2160 and upload from a computer. If you also upload from your phone, keep a 1280×720 JPG under 2 MB — it meets every limit and looks sharp on every screen, because YouTube shows thumbnails far smaller than that.
What happens with the wrong ratio?
A thumbnail that is not 16:9 gets cropped or letterboxed. Square or vertical images lose their edges in the home feed and search results. Use the resizer’s “Fit” mode to keep the whole image on a blurred 16:9 background.
How big does a thumbnail really appear?
On a phone feed it is about the width of the screen; in the Up next sidebar it is around 170 pixels wide. Large text and one clear subject survive that shrink — test it in the thumbnail preview.
Frequently asked questions
What is the best YouTube thumbnail size?
1280×720 pixels as a JPG under 2 MB is the safest choice: it meets the 640-pixel minimum, the 16:9 ratio and the mobile file limit. YouTube recommends 3840×2160 if you upload from a computer.
What is the YouTube thumbnail file size limit?
2 MB when you upload from the YouTube mobile app and 50 MB when you upload from a computer.
Can a YouTube thumbnail be 1920×1080?
Yes. 1920×1080 is 16:9 and above the minimum width. Keep it under 2 MB if you upload from your phone.
Why is my custom thumbnail option missing?
Custom thumbnails require a verified account. Verify your channel in YouTube Studio, then the upload option appears.