Aspect Ratio Calculator
Calculate aspect ratios from width and height. Scale dimensions proportionally. Common presets for screens, photos, and video.
About Aspect Ratio Calculator Tool
This free online aspect ratio calculator computes the simplified ratio (like 16:9) from any width and height, shows the decimal equivalent, finds the greatest common divisor, and lets you scale dimensions proportionally by entering a new width or height. Includes presets for common screen, photo, and video aspect ratios. Perfect for designers, photographers, videographers, and developers working with responsive layouts.
Why Calculate Aspect Ratios?
Aspect ratios are fundamental to visual media: screens (16:9, 21:9), cameras (3:2, 4:3), social media platforms (1:1 Instagram, 9:16 Stories/Reels), and video standards (16:9 HD, 2.39:1 cinema). Knowing the ratio lets you resize images without distortion, plan responsive layouts, set CSS aspect-ratio properties, configure video exports, and create thumbnails at the right proportions.
Key Benefits
- Simplified ratio: Reduces any dimensions to the simplest integer ratio (e.g., 1920×1080 → 16:9)
- Proportional scaling: Enter a new width or height and get the matching dimension
- Common presets: One-click 16:9, 4:3, 1:1, 21:9, 9:16, 3:2, 2:3, and 5:4
- Decimal output: The ratio as a decimal for CSS aspect-ratio and programmatic use
- Instant calculation: No server round-trips
- Completely free: No sign-ups or limits
Privacy and Security
Pure math in your browser. No data is sent to any server. No cookies, no tracking. Free forever.
Ratio calculation
Get the simplified ratio, decimal, and GCD from any width and height.
Fully private
Pure client-side math. Nothing is sent anywhere.
Common presets
16:9, 4:3, 1:1, 21:9, 9:16, 3:2, and more — one click to load.