Width (px)
Height (px)
16:9
Simplified ratio
1.7778
Decimal ratio
177.8%
Width % of height
How it works
The Aspect Ratio Calculator computes the dimensions, ratios, and crop relationships for images and video. Enter any two of width, height, or ratio — the third value is calculated automatically. It's an essential reference for media production, UI design, and responsive layouts.
Aspect ratios govern every display context: 16:9 is standard HD video and most laptop/monitor screens, 4:3 is the classic TV ratio and standard PowerPoint slide, 1:1 is Instagram square, 9:16 is TikTok/Instagram Stories portrait video, 3:2 is 35mm film/DSLR sensor ratio, 4:5 is the Instagram portrait post ratio, 21:9 is ultrawide cinema format.
How to use it: enter width and height in pixels to get the ratio. Enter a ratio and one dimension to get the other dimension. Enter a target ratio and a source image size to get the exact crop dimensions needed to achieve that ratio without distortion.
Common calculations: - "I have a 4000×2667 photo — what is its aspect ratio?" → 3:2 - "I need a 16:9 banner image at 1200px wide — how tall should it be?" → 675px - "I want to crop my 4:3 photo to 16:9 — what area do I keep?" → full width, center crop to 75% of height
Safe zone checker: the tool highlights the safe areas for common platform crops — showing what a given image looks like when cropped to 1:1 (Instagram) or 16:9 (YouTube thumbnail) from its original dimensions.
Reference table: the tool displays a quick reference table of common aspect ratios with their names, decimal equivalents, and typical use contexts.
Privacy: all ratio calculations are pure JavaScript math. No images are uploaded.
Frequently Asked Questions
- 1920×1080px has a 16:9 aspect ratio (1920÷1080 = 1.777... = 16:9 when simplified). 16:9 is the standard for HD and 4K video, most laptop and desktop monitors, YouTube, Vimeo, and streaming platforms.
- From 1200px wide at 16:9, the height would be 1200 × (9/16) = 675px. The crop would be 1200×675px centered on the image, removing 62.5px from the top and bottom. This tool calculates that automatically.
- 1:1 (square) for standard feed posts (1080×1080px), 4:5 (portrait) for full-frame portrait posts (1080×1350px, the maximum fill on mobile feeds), 16:9 (landscape) for landscape posts (1080×608px, shows at full width in feed). Stories and Reels use 9:16 (1080×1920px).
- Enter the pixel width and height in the Width and Height fields. The calculator divides them, finds the GCD (greatest common divisor), and outputs the simplified ratio. A 2560×1600px image → GCD 320 → 8:5 (equivalent to 1.6:1 or the old MacBook Pro display ratio).