📐Aspect Ratio Calculator
Keep an aspect ratio (e.g. 16:9) and enter just the width or height — the other is calculated automatically. Useful for matching video resolutions, thumbnail/banner sizes, image resizing, and monitor/design work. Also reverse-calculates the ratio from two dimensions.
🔒 Browser-based✓ No watermark✓ No signup
How to use
- 1Pick a ratio (e.g. 16:9) or enter your own.
- 2Enter either width or height.
- 3The other dimension is auto-calculated to match the ratio.
FAQ
Can I reverse-calculate a ratio?+
Yes. Enter the current width and height to get the simplified ratio (e.g. 1920×1080 → 16:9).
Which ratios are common?+
16:9 (YouTube/monitors), 9:16 (Shorts/Reels), 4:3 (legacy), 1:1 (Instagram), 3:2 (photography), 21:9 (ultrawide).
What about fractional results?+
Pixels are rounded to integers. If the ratio doesn't divide evenly, the nearest integer is shown.
Can I use it for video resolution?+
Yes. Enter width 1280 at 16:9 and height 720 is computed — handy before encoding or cropping.
Compare multiple ratios at once?+
Use the preset buttons to switch quickly between common ratios.