- Thumbnail size, format and file limit at a glance
- Recommended isn't the same as required
- Why the phone limit catches people out
- The vertical video swap most people miss
- How to upload a custom thumbnail
- Why YouTube refuses or removes a thumbnail
- What I'd do with a business channel
- Frequently asked questions
As of Nov 2026, YouTube Help recommends a custom thumbnail of 3840 x 2160 pixels for videos and 2160 x 3840 for Shorts, saved as a JPG or PNG, with a minimum width of 640 pixels for videos and a minimum height of 640 pixels for Shorts. The file limit depends on the device you upload from: 2 MB for a video thumbnail on a phone, 50MB on a computer.
That's the whole answer in two lines, and it comes straight from YouTube's own Help page on custom thumbnails. The rest of this page covers the bits that trip people up: the gap between a recommended size and a hard limit, what happens to your thumbnail on a vertical video, and why an upload gets refused.
Thumbnail size, format and file limit at a glance
| Type | Recommended size | Minimum | Aspect ratio | Upload limit |
|---|---|---|---|---|
| Video | 3840 x 2160 pixels | 640 pixels wide | 16:9 | 2 MB on a phone, 50MB on a computer |
| Short | 2160 x 3840 pixels | 640 pixels high | 9:16 | Added in YouTube Studio on a computer, where the cap is 50MB |
| Podcast playlist | Not given on the Help page | Not given on the Help page | 1:1 | 10 MB on a phone, 50MB on a computer |
Formats are image files such as JPG or PNG. YouTube's advice is that your thumbnail should be as large as possible, because it's also used as the preview image in the embedded player. So a thumbnail that looks fine in search results can look soft when someone embeds your video on their own website.
Recommended isn't the same as required
Plenty of older guides still quote 1280 x 720 as the YouTube thumbnail size. That number is a video resolution, the 720p row in YouTube's resolution table, and it isn't what the thumbnail Help page recommends now. The current page says 3840 x 2160, which matches the 4K row for 16:9 video.
So what's a hard rule? Only two things on that page: the minimum, 640 pixels wide for videos or 640 pixels high for Shorts, and the file size cap for the device you're using. YouTube doesn't state a maximum pixel size. The Help page gives no safe-zone or text-size guidance either, so any rule you've seen about where text must sit comes from somewhere else, not from YouTube.
Thumbnail size is also separate from the size of the video itself. If you need the resolution and aspect ratio for the video file, that's a different table, and I've covered it in my guide to YouTube video dimensions.
Why the phone limit catches people out
The phone limit is far lower than the computer one: 2 MB for a video thumbnail, against 50MB on a computer. If you design at the recommended size and export a detailed file, the phone upload is the one most likely to refuse it. The simple fix is to upload from a computer.
Podcasts get a slightly bigger phone allowance, 10 MB, but on a computer the limit is the same 50MB for video, Shorts and podcast thumbnails.
The vertical video swap most people miss
This is the one I'd want every business owner to know. YouTube Help says vertical videos with a 16:9 custom thumbnail have it replaced by an auto-generated 4:5 thumbnail on the home, explore and subscription pages.
Your own image still shows on the watch feed, in watch history and on non-mobile platforms. But home, explore and subscriptions are where people browse and decide what to click, and that's exactly where YouTube swaps your design out. If you film vertically, don't count on a horizontal template showing up there. YouTube's own advice for Shorts is a 9:16 thumbnail.
How to upload a custom thumbnail
You need a verified account before you can upload your own image. Without verification you can only pick from the auto-generated suggestions. Verification is a phone check: YouTube sends a code by text or voice call, and says one phone number can be linked to no more than 2 channels per year. If you haven't done it yet, follow these steps to verify your YouTube account first.
- Sign in to YouTube Studio.
- Select Content from the left menu.
- Go to the video you want to edit and open it.
- Below Thumbnail, click Upload file and choose your image, or click Get suggestions to have YouTube generate one.
- Click SAVE.
YouTube says changes can take time to appear, so don't worry if the old image hangs around for a while. If it still won't show, here's what to check when YouTube thumbnails aren't loading.
Shorts work a little differently: custom Shorts thumbnails can only be added in YouTube Studio on a computer, from the Shorts tab under Content, and the account must be verified. I've put the full Shorts walkthrough in my guide to changing a YouTube Short thumbnail.
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There's also Ask Studio, which YouTube says can suggest thumbnails by analysing your video's transcript and themes. You type a prompt such as "Create a thumbnail", add the video or reference images, and ask for changes in follow-up prompts, for example making the text bigger.
Why YouTube refuses or removes a thumbnail
- Daily limit. If you see "Daily custom thumbnail limit reached", YouTube says to try again in 24 hours. The limit varies by country or region and by channel history.
- Strikes. Copyright strikes can affect channel history, and Community Guidelines strikes affect how many custom thumbnails you can upload.
- Policy. Thumbnails with nudity or sexually provocative content, hate speech, violence or harmful or dangerous content can be rejected and bring a strike. Repeat offences can remove custom thumbnail privileges for 30 days or even lead to the account being terminated.
- Search results. YouTube may turn off custom thumbnails for certain search results when it considers them inappropriate for viewers.
If a strike arrives, you'll get an email and an alert in Channel Settings. You can appeal if you think the thumbnail didn't break the rules, and if the appeal is approved and you haven't replaced the image yet, YouTube says it may restore it.
What I'd do with a business channel
I'd keep one master file at 3840 x 2160 for every long-form video, saved as a JPG or PNG, and upload it from a computer so the 2 MB phone cap never comes into it. I'd make a separate 9:16 version for Shorts and vertical videos instead of hoping the 16:9 one survives on the home page. And I'd verify the channel well before launch day, not the morning you publish.
Skip the hunt for a secret perfect size. YouTube's page gives you a recommendation, a minimum and a file cap, and that's all there is. Your time is better spent on what the image says and whether it makes someone want to click.
If you run a YouTube channel for your business and want the video side planned sensibly, that's the kind of content strategy I help with. I run AI training and workshops for teams, and help businesses with AI enablement and workflow automation, so the busywork runs itself and people get time back. Most of that work is with SaaS marketing teams and small businesses. Here's how we can work together.
Frequently asked questions
What size is a YouTube thumbnail in 2026?
As of Nov 2026, YouTube Help recommends 3840 x 2160 pixels for videos and 2160 x 3840 for Shorts, with a minimum width of 640 pixels for videos and a minimum height of 640 pixels for Shorts.
What's the file size limit for a YouTube thumbnail?
It depends on the device. On a phone it's 2 MB for a video thumbnail or 10 MB for a podcast. On a computer it's 50MB for video, Shorts and podcast thumbnails.
Is 1280 x 720 still the right YouTube thumbnail size?
YouTube's thumbnail Help page now recommends 3840 x 2160 for videos. 1280 x 720 is the 720p video resolution, not the thumbnail recommendation.
Why did my thumbnail change on a vertical video?
YouTube replaces a 16:9 custom thumbnail on a vertical video with an auto-generated 4:5 thumbnail on the home, explore and subscription pages. Your own image still shows on the watch feed, watch history and non-mobile platforms.
Do I need a verified account for a custom thumbnail?
Yes. You can pick from auto-generated suggestions without it, but uploading your own image needs a verified account.
