Aspect Ratio Calculator
Calculate missing dimensions for any aspect ratio — 16:9, 4:3, custom — instantly.
Loading tool…
About this tool
Enter any two values and get the rest: scale a 16:9 video to any width, find the height for a 1200px-wide 1.91:1 OG image, or compute the ratio of arbitrary dimensions. Includes one-click presets for common web, video and social sizes.
How to use the Aspect Ratio Calculator
- Pick a preset ratio or enter your original dimensions.
- Type the new width (or height).
- Read the matching dimension — rounded to whole pixels.
Frequently asked questions
Why do aspect ratios matter for CLS?
Setting width and height attributes (or aspect-ratio CSS) reserves space so images don’t shift the layout while loading.
What ratio for social share images?
1.91:1 (1200×630) for OG/link cards; 1:1 and 4:5 for Instagram feed.