Checked on October 4, 2026, based on YouTube Help.
Check these first
- Account verification: you can upload custom thumbnails only after verifying your account.
- File size: 2 MB when uploading from mobile, 50 MB from desktop.
- Format: JPG or PNG. Avoid GIF and WebP.
- Ratio and size: 16:9 for videos, 9:16 for Shorts. Smaller than 640px wide (640px tall for Shorts) will look blurry.
Symptoms, causes and fixes
| Symptom | Likely cause | Fix |
|---|---|---|
| The upload button is grayed out | Account not verified | Verify your account with a phone number in YouTube Studio |
| The upload fails right away | File too large or wrong format | Save as JPG and keep it under 2 MB |
| Uploaded, but the old image still shows | Processing delay or cache | Refresh after a few minutes; clear the app cache |
| "Daily limit" error | Too many changes today | Try again after 24 hours |
| The thumbnail is rejected | Possible policy violation | Edit the image so it follows YouTube policies |
It uploaded but nothing changed
YouTube Help notes that thumbnail changes can take some time to appear. Refresh after a while. The mobile app often caches images, so fully closing and reopening the app or clearing its cache can make the new thumbnail appear right away.
"Daily custom thumbnail limit" error
There is a limit on how many custom thumbnails you can upload per day, and YouTube asks you to try again in 24 hours. If you are refreshing thumbnails for many videos, do a few per day.
Rejected for policy reasons
Thumbnails with nudity, hate speech, violence or harmful or dangerous content can be rejected. Shock images may bring short-term clicks, but violations can hurt the whole channel. Use an image that matches the video.
Maybe it's your browser or app
If uploads keep failing, cache or extensions in your browser can be the cause. Try a private window or another device (computer vs. phone). If it fails on both, the file itself (size, format or ratio) is the likely problem.
Prevent it before you upload
Check the file size and pixel dimensions in the file properties before uploading. If you make the thumbnail in the YouTube Thumbnail Maker, it starts at 1280×720 and can auto-compress JPG to under 2 MB, so these conditions are met automatically.
Checklist
- Is your account verified?
- Is it JPG or PNG and under 2 MB (mobile)?
- Is the ratio 16:9 or 9:16?
- Does the image match the video?
- Have you already changed many thumbnails today?
FAQ
I changed the thumbnail, but search results still show the old one.
Search engines and other services can cache the previous image for a while. YouTube itself usually updates first; others catch up over time.
Why is the custom thumbnail option missing?
Usually because the account isn't verified yet. Verify it in YouTube Studio with a phone number and the option appears.
My thumbnail is 3 MB. Will it upload?
From a computer, yes (limit 50 MB). From the mobile app, no (limit 2 MB). Save it as JPG at 80–90% quality or at 1280×720 to get under 2 MB.