Calculate image aspect ratios for video and photos
What is the Aspect Ratio?
The aspect ratio works like this: it computes the missing dimension from an aspect ratio and one known side, covering common ratios plus custom. Everything happens on your device - the input never leaves your tab unless the tool clearly states it performs a server-side lookup.
How to use the Aspect Ratio
Select or drop your image.
Adjust the available settings while watching the preview.
Check dimensions, quality and format before exporting.
Download the result and keep the original when quality matters.
Features
Runs on your device via the Canvas and WebAssembly APIs
Batch-friendly when you have several files
Original images stay untouched
Common mistakes to avoid
Over-compressing images that contain small text
Exporting transparency to JPEG
Examples
Input
Result
16:9 with width 1920
Height 1080 · also shows 4:3 and 1:1 equivalents
Best used for
Getting a reliable answer for aspect ratio without installing an app
One-off tasks done in under a minute from any device
Checking results before committing them to something important
Working on a phone where desktop software is unavailable
Privacy
Images are processed on your device; nothing is uploaded unless a tool explicitly says a server lookup is involved.
Frequently asked questions
Why do platforms crop my photos?
Feeds force fixed ratios - computing the exact pixel height for the target ratio tells you what will be cropped.
How does the missing-dimension calculation work?
Enter the ratio (like 16:9) and one known side - the other side is computed from the proportion, covering common ratios plus any custom pair.
When do I need this instead of mental math?
Cropping, resizing and print work - a 3:2 photo at 1200px wide must be 800px tall, and the calculator keeps every such pair straight.