Aspect Ratio Calculator
Find the aspect ratio of any width and height, and resize proportionally — enter a new width to get the matching height (or vice versa). Includes presets like 16:9, 4:3, and 1:1.
16 : 9
Aspect ratio
1.7778
Decimal (w ÷ h)
Type a width to get the matching height, or vice versa.
About This Tool
Aspect ratio — the proportional relationship between width and height — quietly governs how images and video look on every screen. Get it wrong and photos stretch, videos show black bars, or thumbnails crop awkwardly. This calculator takes the guesswork out.
What the ratio tells you
An aspect ratio like 16:9 means 16 units of width for every 9 of height. The tool reduces any width and height to their simplest ratio (1920×1080 becomes 16:9) and also shows the decimal ratio, which is handy for calculations.
Resizing without distortion
The most common real task is resizing while keeping proportions. Enter your original dimensions, then type a new width and the tool computes the matching height (or the reverse). Because the ratio is preserved, the result never stretches or squashes.
Ratios worth knowing
- **16:9** — modern video, YouTube, monitors, TVs - **4:3** — older screens, many cameras, presentations - **1:1** — square posts (Instagram feed) - **9:16** — vertical video, Reels, TikTok, Stories - **21:9** — ultrawide monitors and cinematic video
Use the presets to snap to a common ratio, then resize to the exact pixels you need. Everything is calculated in your browser.
Frequently Asked Questions
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Last updated: August 8, 2026