Last updated: 2026-05-25

Understanding Aspect Ratio

The aspect ratio describes the proportional relationship between the width and height of a rectangle. Enter any width and height to get the ratio as a clean fraction, or pick a preset to see standard dimensions for common screens, cameras, and platforms.

How It Works

The result is simplified to the lowest-integer fraction using the greatest common divisor, so 1920 × 1080 becomes 16/9 rather than 1920/1080.

Common Aspect Ratios

Practical Uses

Video production — Before exporting, confirm your canvas matches your delivery platform. YouTube and Netflix require 16:9; Instagram Reels and TikTok expect 9:16.

Photo printing — A 4×6 print is 3:2; a 5×7 print is roughly 7:5. Knowing the ratio prevents unexpected cropping when ordering prints from a square camera sensor.

Screen design — UI mockups must match the target device. A phone screen is typically 9:16 or 19.5:9 (modern edge-to-edge); a desktop is usually 16:9.

Projector setup — Check whether a projector is 4:3 or 16:9 before placing the screen, or part of the image will be cut off or letterboxed.

Resizing without distortion — Keep the same ratio when scaling: if the original is 1280 × 720 (16:9), scale to any width W and height W × (9/16).

For related tools, see Ratio & Proportion Calculator (scale any two quantities proportionally) and Gear Ratio Calculator (mechanical drive ratios).