YouTube Thumbnail Size: Dimensions, Aspect Ratio and File Limits (2026)

The recommended YouTube thumbnail size is 3840 × 2160 pixels at a 16:9 aspect ratio, uploaded as a JPG or PNG. The minimum width is 640 pixels. The classic 1280 × 720 still works and is what most channels upload. Shorts thumbnails are vertical: 2160 × 3840 at 9:16.

YouTube's help page now recommends 4K instead of the 1280 × 720 it listed for years, and allows up to 50 MB when you upload on a computer (2 MB from a phone). Most guides still quote only the old numbers. Below are the current specs, the limits that differ between desktop and mobile, and which size to actually export.

YouTube thumbnail specs at a glance

Podcast playlists are the exception to 16:9: YouTube asks for a square 1:1 image there, with a 10 MB limit on mobile.

3840 × 2160 or 1280 × 720?

Both are 16:9, so they look identical in shape. The difference is sharpness on large screens.

On a phone the thumbnail is shown about 360 pixels wide, and on a desktop home page about 400. At those sizes 1280 × 720 already carries three times more detail than the screen can show. Export at 4K only if you design at that size; upscaling a 720p image to 3840 × 2160 makes the file bigger without making it sharper.

Check your audience before you decide. In YouTube Studio Analytics, the device type report shows how much of your watch time comes from TV screens. If it is a large share, 4K thumbnails are worth the extra export step.

File size limits: desktop vs mobile

The limit depends on where you upload, not on the thumbnail:

• YouTube Studio on a computer: 50 MB for video, Shorts and podcast thumbnails.
• YouTube or YouTube Studio app on a phone: 2 MB for video thumbnails, 10 MB for podcasts.

If a phone upload fails with a file size error, re-export the image as a JPG at 80–90% quality. A 1280 × 720 JPG almost always lands under 2 MB. PNG files are larger because they are lossless, so save PNG for thumbnails with flat colors and sharp text where JPG compression would show.

YouTube Shorts thumbnail size

Since July 2026 you can upload a custom thumbnail for a Short. It has to be vertical: 2160 × 3840 at 9:16 is recommended, and the minimum height is 640 pixels. A 1080 × 1920 frame works well and matches the size most Shorts are exported at.

Two limits to know. Shorts thumbnails can only be added in YouTube Studio on a computer, and YouTube's A/B test for thumbnails does not support Shorts. If you upload a 16:9 thumbnail to a vertical video, YouTube replaces it with an automatic 4:5 crop. The step-by-step is in how to add a thumbnail to YouTube Shorts.

How the thumbnail is cropped and covered

Your 16:9 image is not always shown whole. Plan for three things:

• The timestamp. The video length sits in the bottom-right corner on every surface. Keep text and faces out of the bottom-right 15%.
• The progress bar. A red bar runs along the bottom edge for viewers who started the video.
• Small sizes. In the sidebar of the watch page the thumbnail is about 170 pixels wide. Text below roughly 1/8 of the image height becomes unreadable there.

The safest layout puts the main face or object on one side, two to four words of text on the other, and leaves the bottom-right corner empty. For layouts that work in different niches, see our YouTube thumbnail ideas.

How to resize an image to YouTube thumbnail size

1. Crop to 16:9 first. In any editor, lock the crop ratio to 16:9 so nothing is stretched.
2. Resize to 1280 × 720, 1920 × 1080 or 3840 × 2160. Downscaling is always safe; upscaling a small image adds no detail.
3. Export as JPG at 80–90% quality, or PNG for flat graphics.
4. Check the file size against the limit for the device you will upload from.

If you are making the thumbnail from scratch, start at the final size so nothing needs resizing later. Short.now's AI thumbnail maker generates 16:9 thumbnails and downloads them as a 1280 × 720 JPG under 2 MB, which uploads from both desktop and phone. It also makes 9:16 images for Shorts.