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Free Video Aspect Ratio Calculator for YouTube

Type a width and a height, or open a video or an image, and get its aspect ratio (16:9, 9:16, 4:5, 1:1, 21:9...), the same shape at common resolutions, the exact crop or black bars to turn it into 16:9 or 9:16, the window to cut a Short out of a horizontal video and the FFmpeg commands to do each one. Everything runs in your browser: your file never leaves your device.

Updated · Built by Kevin Tabares, long-form YouTube editor at Umbrella Creators. YouTube sizes from YouTube Help, read October 21, 2026.

Calculate the aspect ratio of a video size

Your file stays on your device. Nothing is uploaded: your browser reads only the size stored in the file and draws one small frame, right here in this tab.

The same shape at common sizes

Size (pixels)Note

Change the shape

Make a Short from this video

Run the commands in the folder where your file is (for a typed size, replace input.mp4 with your file's name). If FFmpeg says it cannot copy the audio, change -c:a copy to -c:a aac -b:a 384k.

How to use it

  1. Type the width and the height in pixels, or open the video or image to read them from the file. A file with non square pixels or a rotation flag is shown at the size it plays at.
  2. Read the aspect ratio, its name and what YouTube Help says about that shape, then look up the same shape at common sizes.
  3. Pick the shape you need (16:9, 9:16, 1:1 or 4:5) and the output size. You get the black bars version, the cropped version with the exact crop rectangle, a plain resize and the FFmpeg command for each one. For a horizontal video, move the 9:16 window to your subject to cut a Short.

Every size and position in the results is an even number, because the usual H.264 export format needs even sizes. Shapes within 0.5% of the one you pick are treated as the same shape: the tool just resizes them, which stretches the picture by about 0.5% at most (under 10 pixels across a 1920 pixel wide frame).

What YouTube Help says about shapes and sizes

TopicYouTube Help (read October 21, 2026)
VideosThe standard aspect ratio for YouTube on a computer is 16:9; with other shapes, like vertical or square, the player adapts to the video (upload encoding settings).
16:9 sizes7680 x 4320 (4320p, 8K), 3840 x 2160 (2160p, 4K), 2560 x 1440 (1440p), 1920 x 1080 (1080p), 1280 x 720 (720p), 854 x 480 (480p), 640 x 360 (360p), 426 x 240 (240p) (video resolution and aspect ratios).
Black barsAvoid adding padding or black bars to the video itself: they stop the player from adapting to the video and the device (same page).
ShortsSquare or vertical, up to 3 minutes (upload Shorts). To keep a video out of Shorts, use a wider shape such as 16:9 (three minute Shorts).
Video thumbnails16:9, 3840 x 2160 recommended, at least 640 pixels wide (custom thumbnails).
Shorts thumbnails9:16, 2160 x 3840 recommended, at least 640 pixels tall. A vertical video with a 16:9 thumbnail gets an automatic 4:5 one on the home, explore and subscription pages (same page).
Podcast playlists1:1 thumbnails (same page).

FAQ

How do I work out the aspect ratio of a video?
Divide the width and the height by the largest number that goes into both. For 1920 x 1080 that number is 120, so the ratio is 16:9; for 1080 x 1350 it is 270, so 4:5. As a decimal, divide the width by the height: 1920 / 1080 = 1.778. A size that does not reduce to a short ratio, like 1081 x 1921, is compared with the nearest common shape: that one is 9:16 to within 0.04%.
What aspect ratio and resolution should a YouTube video have?
YouTube Help says the standard aspect ratio for YouTube on a computer is 16:9, and that the player adapts to other shapes like vertical or square. For 16:9 it lists 7680 x 4320 (4320p), 3840 x 2160 (2160p, 4K), 2560 x 1440 (1440p), 1920 x 1080 (1080p), 1280 x 720 (720p), 854 x 480, 640 x 360 and 426 x 240 (YouTube Help, read October 21, 2026).
What aspect ratio is a YouTube Short?
Square or vertical, up to 3 minutes long (YouTube Help, read October 21, 2026). YouTube also says that if you do not want a video to count as a Short, you should use a wider shape such as 16:9 (YouTube Help). The calculator makes Shorts at 1080 x 1920, and YouTube Help notes, in its steps for the YouTube app, a maximum resolution of 1080p for Shorts (YouTube Help).
Should I add black bars to make my video 16:9 for YouTube?
Not for a normal upload. YouTube Help asks you to avoid adding padding or black bars to the video itself, because that stops the player from adapting to your video's shape and the viewer's screen (YouTube Help, read October 21, 2026). The black bars option here is for when you place a clip with another shape inside a 16:9 or 9:16 edit.
What size should a YouTube thumbnail be?
YouTube recommends 3840 x 2160 for video thumbnails and 2160 x 3840 for Shorts, with at least 640 pixels of width for videos and 640 of height for Shorts; 16:9 for videos, 9:16 for Shorts and 1:1 for podcast playlists. A vertical video with a 16:9 custom thumbnail gets an automatic 4:5 thumbnail on the home, explore and subscription pages (YouTube Help, read October 21, 2026). Type your thumbnail size here to check its shape.
Why are all the sizes in the FFmpeg commands even numbers?
Because FFmpeg's H.264 encoder needs them in the usual 4:2:0 color format. In a test with FFmpeg 8.1 on October 21, 2026, its H.264 encoder (libx264, yuv420p) refused a 1081 x 1921 picture with "width not divisible by 2", and its crop and pad filters moved odd positions to the even position just before them. So every size and position the calculator gives is even, which can leave one bar a couple of pixels bigger than the other.
Does it upload my file?
No. When you open a file, your browser reads only the part of it that stores the size (for an MP4 or MOV, the header, usually a few megabytes even for an hour long video) and draws one small frame for the diagrams. Nothing leaves your device.

Who made this

I'm Kevin Tabares. I've edited long-form YouTube videos since 2015 (1,277 videos and 152.2M+ views tracked on YT Jobs) for channels like Rex & Alexa, Puff and Mud. I built this calculator so anyone can get the exact numbers for a crop, black bars or a Short in seconds, without uploading anything. If you want an editor for your channel, get in touch.

More free tools

A Shorts crop preview to place a 9:16 crop on your video, a black bars checker, an export settings calculator and a thumbnail preview, all free and without signup.

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