Free tool
Aspect ratio calculator 16:9, 9:16, 4:5 and any pixel size.
Type what you know. Get the missing side, the simplified ratio, and the export size each platform expects.
Resize by ratio
1920 × 1080
16:9, landscape, 1.778 to 1.
Common sizes:
Ratio from pixels
4:5
0.8 to 1, portrait. Exactly 4:5.
Fit into another frame
Calculated as you type.
Aspect ratio calculator at a glance
content.win works out ratios, free, with the platform sizes built in.
- Works with
- A ratio, a width or a height, or a pixel size.
- Comes back as
- The missing side, the ratio, and the sizes each platform wants.
- Runs
- In your browser.
- Limits
- No limit.
- Price
- Free. No account.
The sizes each platform wants
Same footage, different frame. These are the export sizes, from each platform's current specs.
- Reels, TikTok, Shorts, Stories
- 9:16, export 1080 by 1920. Keep text out of the top and bottom 250 pixels where the interface sits.
- Instagram feed
- 4:5 portrait, 1080 by 1350, takes the most screen. Square is 1:1 at 1080 by 1080. Landscape posts are 1.91:1 at 1080 by 566.
- YouTube
- 16:9, 1920 by 1080 or 3840 by 2160. Thumbnails 1280 by 720.
- X
- 16:9 images at 1600 by 900 display best; video up to 1920 by 1200.
- 1.91:1 link images at 1200 by 627; 4:5 and 1:1 posts also display well.
- 2:3 at 1000 by 1500. Taller pins get cut off in the feed.
How the maths works
- Resize: multiply the side you have by the ratio. Height equals width times ratio height over ratio width.
- Ratio from pixels: divide both sides by their greatest common divisor. 1920 and 1080 share 120, leaving 16 and 9.
- Fit: scale the source until one side touches the frame, then the other side's leftover is the bar.
- Pixels have to be whole and, for video, even. The calculator rounds and tells you when a result is not exact.
Questions people ask
What is an aspect ratio?
The proportion between width and height, written width:height. A 1920 by 1080 video is 16:9 because both numbers divide by 120. The ratio says nothing about size, only shape.
How do I calculate the missing height or width?
Multiply the side you know by the ratio. For 16:9 at 1280 wide, height is 1280 times 9 divided by 16, which is 720. The calculator does this as you type and rounds to whole pixels, then tells you if the rounding made it a hair off.
What's the difference between 16:9 and 9:16?
The same shape turned on its side. 16:9 is landscape: YouTube, TV, monitors. 9:16 is portrait: Reels, TikTok, Shorts and Stories. 1080 by 1920 is 9:16.
Why is Instagram 4:5?
A 4:5 portrait fills more of the phone screen in the feed than a square or a landscape image, so it gets more attention per scroll. 1080 by 1350 is the standard export.
Will changing the ratio distort my image?
Resizing to the same ratio never distorts. Changing the ratio means cropping or adding bars. The Fit section shows exactly how much: the size your footage becomes inside the new frame and the bars left over.
What does 2.39:1 mean?
The cinematic widescreen ratio, also written 2.40:1. On a 16:9 screen it shows as black bars top and bottom. Creators use it as a look; it comes at the cost of about a third of the vertical space.
Why do I sometimes get odd numbers like 1919 by 1080?
Because a ratio like 16:9 doesn't divide evenly into every width. Encoders need even numbers, so round to the nearest even value. The calculator flags any result that isn't exact.