Aspect Ratio Calculator
Calculate aspect ratios and resize dimensions proportionally. Everything runs in your browser.
16:9
Common sizes at this ratio:
What Is an Aspect Ratio?
An aspect ratio is the proportional relationship between width and height. It's expressed as two numbers separated by a colon (e.g., 16:9). The ratio stays constant regardless of the actual pixel dimensions — a 1920x1080 image and a 3840x2160 image are both 16:9.
Common Aspect Ratios
- 16:9 — Standard widescreen. HD video (1920x1080), 4K (3840x2160), YouTube, most monitors.
- 4:3 — Classic TV and older monitors. Still used in presentations and some tablets (iPad).
- 1:1 — Square. Instagram posts, profile pictures, album art.
- 9:16 — Vertical video. TikTok, Instagram Reels, YouTube Shorts, phone screens.
- 21:9 — Ultrawide. Cinema screens, ultrawide monitors.
- 3:2 — Photography standard. DSLR sensors, Surface devices.
Why Aspect Ratio Matters
- Responsive design — Ensuring images and videos maintain proportion across screen sizes.
- Social media — Each platform has preferred dimensions. Wrong ratios get cropped.
- Video production — Mixing footage of different ratios requires letterboxing or cropping decisions.
- Print design — Paper sizes have specific ratios (A4 is approximately 1:1.414).