Aspect Ratio Calculator
Keep proportions locked while resizing. Pick a ratio, enter a width or height, and get the matching dimension — or derive the ratio from an existing size.
aspect-ratio: 16 / 9;About the aspect ratio calculator
Work out missing dimensions while keeping an aspect ratio locked. Enter a ratio (or pick a common one like 16:9), give one dimension, and get the other — perfect for resizing video, images and layout boxes without distortion.
All math runs in your browser.
Enter width or height and get the matching value for your ratio.
16:9, 4:3, 1:1, 21:9, 3:2 and more, one click away.
Derive and simplify the ratio from two dimensions.
Calculated entirely in your browser.
Frequently asked questions
How do I keep an aspect ratio when resizing?
Divide by the ratio: for 16:9, height = width × 9 ÷ 16. Enter one dimension and the calculator gives the other so the proportions stay identical.
What is 16:9 in pixels?
Any size where width ÷ height = 16 ÷ 9 — e.g., 1920×1080, 1280×720 or 1600×900. The tool computes exact matches for any width or height.
Can it tell me the ratio of an existing size?
Yes. Enter both dimensions and it derives and simplifies the ratio (e.g., 1920×1080 → 16:9).
Is anything uploaded?
No. All calculations happen in your browser.