What is the YouTube thumbnail size?

1280x720 pixels, a ratio of 16:9. YouTube accepts anything from 640x360 upwards at that shape and shows all of it in the same slots, so the larger number is simply the one that still holds up on a television.

What if my image is not 1280x720?

A widescreen file at any size is scaled to fit and holds up down to about 640 pixels wide. A file of a different shape is padded into the wide slot instead, which costs you the space those bars take.

Is my image uploaded when I check it?

No. The file is opened by your own browser, measured, and forgotten when you close the tab. It is never sent to us, so there is nothing on our side to keep, leak or delete.

Why was my YouTube thumbnail rejected?

Usually file size, and where you uploaded from decides which ceiling you met: a desktop browser allows 50 MB while the mobile app stops at 2 MB, which a large PNG passes easily. Re-export the same image as a JPEG at around quality 85 and it drops to a fraction of that with no visible difference. The other two causes are an account you have not phone-verified, which blocks custom thumbnails entirely, and a format outside JPG and PNG.

Yes. This tool does its work in your browser, so whatever you type, paste or upload stays on your device. Nothing is sent to our servers, which is also why it keeps working if you go offline after the page has loaded.

Yes. Every tool here is free with no account, no credit card and no usage cap. They exist so that the people who need our scheduling product find us, which only works if the tools are genuinely useful on their own.

Do I need an account?

No. Open the page and use it. An account is only for OctoSpark itself, where you plan, schedule and publish a whole calendar rather than fixing one post at a time.

Can I use the output commercially?

Yes. Anything you produce here is yours, including for client and commercial work. We claim no rights over it and we do not watermark it.

OctoSpark

Free tool — runs in your browser

YouTube thumbnail size

The YouTube thumbnail size is 1280x720 pixels, a ratio of 16:9. Measure your artwork here, in the browser, and see how it holds up at sidebar thumbnail scale.

Every YouTube thumbnail size

Every YouTube thumbnail size, with its pixels, its ratio and what it is for.
Where it is used	Pixels	Ratio	What the number is for
Video thumbnail	1280x720	16:9	What the search page, the sidebar, the home grid and your channel page all draw.
The size YouTube now asks for	3840x2160	16:9	The resolution named in the current requirements, and the one to export at when the design has fine type in it.
Shorts cover	1080x1920	9:16	Vertical, and a separate design rather than a crop of the wide one.
Smallest accepted thumbnail	640x360	16:9	YouTube takes it, then shows it everywhere the large one goes, including a television.

Check an image you already have

Check it against

Choose an imageIt is measured on this device and never uploaded.

Choose a file and this says whether it fits, and what gets cropped if it does not.

Resize it to these pixels

Every YouTube thumbnail size, in pixels

A thumbnail is made at one size and judged at about a fifth of it, which makes the pixel count the easy half of this question and legibility in a sidebar the half that decides anything.

Video thumbnail: 1280x720px, a ratio of 16:9. What the search page, the sidebar, the home grid and your channel page all draw.
The size YouTube now asks for: 3840x2160px, a ratio of 16:9. The resolution named in the current requirements, and the one to export at when the design has fine type in it.
Shorts cover: 1080x1920px, a ratio of 9:16. Vertical, and a separate design rather than a crop of the wide one.
Smallest accepted thumbnail: 640x360px, a ratio of 16:9. YouTube takes it, then shows it everywhere the large one goes, including a television.
The file size ceiling depends on where you upload from: 50 MB in a desktop browser and 2 MB in the mobile app. That gap is the rule people trip, because a flat PNG that Studio accepted on a laptop is refused when a collaborator retries it from a phone.
YouTube asks for JPG or PNG, and a thumbnail is a still in every slot it appears in, so there is no format here that buys you movement.
The same file is drawn at roughly 360 pixels wide in a sidebar and smaller again in a mobile search result, which puts the practical ceiling at three or four large words.
YouTube now names 3840x2160 as the resolution to supply, so 1280x720 has gone from being the recommendation to being a comfortable floor above the 640 pixel minimum.
Custom thumbnails need a phone-verified account rather than the tick beside a channel name. Until you verify, YouTube picks a frame out of the video for you.

Check a file you already have against the YouTube thumbnail size

The upload dialog tells you a thumbnail failed only after you have waited for it, and it never tells you that a passing thumbnail will be unreadable in a sidebar. Measuring the file answers both questions in a second.

Pick the target first. This page carries 4 YouTube thumbnail sizes, and a verdict only means something against one of them.
Choose your image. It is opened by this browser tab and measured on a canvas, so the file never leaves the machine you are sitting at and there is no queue or upload to wait for.
Read the result: an exact match at 1280x720, the same 16:9 shape at a different scale, or a crop with the axis that loses pixels named.
If it is wrong, open the YouTube resizer linked underneath. It exports to these exact numbers instead of leaving the decision to the platform.
Then shrink the browser window until the preview is about the width of a sidebar suggestion and read it there. Anything you cannot make out at that size is doing no work at full size either.

What YouTube does when the shape is wrong

YouTube is forgiving about what it accepts and unforgiving about how it shows it. A thumbnail that is not the wide shape gets letterboxed into a wide slot, and that slot is what appears everywhere.

A square or vertical thumbnail is padded into the wide slot, so you are paying for black bars down each side with space you could have used.
A still grabbed from a 720p video is already at the limit, so any crop into it becomes an upscale and the compression pass afterwards finds every soft edge.
Hitting the mobile ceiling of 2 MB refuses the upload outright, with no hint about which file did it. Exporting as JPEG at around quality 85 makes the problem disappear on any device.

What a correctly sized thumbnail still cannot do

Thumbnails are the most over-optimised image in this catalogue and the least decided by pixels. Reaching the right dimensions takes a minute, and the rest of the work is contrast, one idea, and a subject big enough to read while scrolling.

A thumbnail competes in a grid of twenty others, so it is judged against its neighbours rather than on its own. Open the results page for your topic and see what yours has to sit beside.
The title carries half the click and wraps at about sixty characters on a phone, so repeating the title inside the image usually wastes the image.
If it has to carry a face and type, build it at full size in a design tool. Shrinking a finished graphic shrinks the type along with it.

The rest of the job

You just fixed one post. Now do the month.

The youtube thumbnail size solves one piece of one post. OctoSpark plans, writes and schedules the whole calendar across every network you use, publishes it for you, and reports what actually performed.

One calendar for every network
Schedule once, publish everywhere
Drafts written in your own voice
See what actually performed

Open the full sign-up page

No card needed. These tools stay free either way.

Frequently asked questions

How this tool works, what it cannot do, and what happens to what you put into it.

What is the YouTube thumbnail size?
1280x720 pixels, a ratio of 16:9. YouTube accepts anything from 640x360 upwards at that shape and shows all of it in the same slots, so the larger number is simply the one that still holds up on a television.
What if my image is not 1280x720?
A widescreen file at any size is scaled to fit and holds up down to about 640 pixels wide. A file of a different shape is padded into the wide slot instead, which costs you the space those bars take.
Is my image uploaded when I check it?
No. The file is opened by your own browser, measured, and forgotten when you close the tab. It is never sent to us, so there is nothing on our side to keep, leak or delete.
Why was my YouTube thumbnail rejected?
Usually file size, and where you uploaded from decides which ceiling you met: a desktop browser allows 50 MB while the mobile app stops at 2 MB, which a large PNG passes easily. Re-export the same image as a JPEG at around quality 85 and it drops to a fraction of that with no visible difference. The other two causes are an account you have not phone-verified, which blocks custom thumbnails entirely, and a format outside JPG and PNG.
Is my data private?
Yes. This tool does its work in your browser, so whatever you type, paste or upload stays on your device. Nothing is sent to our servers, which is also why it keeps working if you go offline after the page has loaded.
Is this really free?
Yes. Every tool here is free with no account, no credit card and no usage cap. They exist so that the people who need our scheduling product find us, which only works if the tools are genuinely useful on their own.
Do I need an account?
No. Open the page and use it. An account is only for OctoSpark itself, where you plan, schedule and publish a whole calendar rather than fixing one post at a time.
Can I use the output commercially?
Yes. Anything you produce here is yours, including for client and commercial work. We claim no rights over it and we do not watermark it.