Aspect Ratio Calculator
Runs on your device. Nothing is sent.Nothing is uploaded - files are measured on your device, even offline.
Ratio of a size
16:9
- As a decimal
- 1.778:1
- Nearest standard
- 16:9 exactly
- Orientation
- Landscape
- Pixels
- 2.07 MP
Resize without stretching
1280 × 720
Common sizes with this ratio
Fit into a frame
Put the 1920 × 1080 picture into a frame of another shape - with bars, or cropped to fill it - exactly as FFmpeg would.
- Picture is scaled to
- 3414 × 1920
- Cut off
- 1167 px left, 1167 px right
- 68.37% of the picture is cut off.
FFmpeg
ffmpeg -i input.mp4 -vf "scale=1080:1920:force_original_aspect_ratio=increase:force_divisible_by=2,crop=1080:1920" output.mp4CSS (for <img> and <video>)
object-fit: cover;Find the aspect ratio of any size or image, resize without stretching, and fit a picture into a 16:9 or 9:16 frame with bars or a crop.
The aspect ratio is a picture's shape: its width compared with its height. Type a size - or open a photo or video, which is measured on your device without uploading - to get the simplest ratio, the decimal form and the nearest standard like 16:9 or 4:5. Then work out a new size that keeps the shape, rounded the way video encoders want, or see exactly how a picture fits into another frame: with black bars, or cropped to fill, together with the FFmpeg command that does it.
Frequently asked questions
How do I calculate an aspect ratio?
Divide the width and the height by their greatest common divisor. For 1920 × 1080 that's 120, giving 16:9. Some sizes don't reduce neatly - 1366 × 768 is 683:384 - so the calculator also names the nearest standard ratio and how far off it is.
How do I resize without stretching?
Keep the ratio: new height = new width × height ÷ width. For 16:9 at 1280 wide that's 1280 × 9 ÷ 16 = 720. Type either the width or the height and the other is worked out; choose rounding to whole or even pixels, since you can't have half a pixel.
Why do video sizes need to be even?
H.264 and most other encoders store colour at half resolution, so width and height must be divisible by 2 - an odd size makes FFmpeg stop with an error. Older workflows wanted multiples of 16. The calculator rounds for you and shows how far that moves the ratio.
Should I fit or fill a vertical 9:16 frame?
Fit keeps the whole picture and adds bars where it doesn't reach; fill covers the frame and cuts off whatever sticks out. A 16:9 video in a 1080 × 1920 Reels or TikTok frame either shrinks to 1080 × 608 with big bars, or is cropped to a strip of the middle - the calculator shows exactly how many pixels each way.
Is 21:9 really 21:9?
Not quite. Monitors sold as 21:9 are 2560 × 1080 or 3440 × 1440, which are 64:27 (2.37:1) and 43:18 (2.39:1). Cinema widescreen is 2.39:1. That's why the calculator shows the exact ratio next to the familiar name.
Are my images uploaded?
No. A file you open is only read by your browser to get its pixel size; nothing is sent anywhere and the page works offline.