Aspect Ratio Calculator
Calculate missing dimensions, simplify ratios, and compare frame sizes for responsive design and media planning.
Enter a ratio such as 16:9, 4:3, 1:1, or 1.91:1, then provide a width, a height, or both. The calculator simplifies the ratio, fills in the missing dimension, and shows a short check so you can verify image, video, ad, and layout sizes before exporting assets.
Choose a starting point or leave Custom ratio and type your own ratio values.
Leave one dimension blank to calculate it, or enter both dimensions to check how closely they match the selected ratio.
How it works
Ratio width and Ratio height define the shape. A 16:9 ratio means every 16 units of width pair with 9 units of height, regardless of whether the final asset is measured in pixels, points, or another unit.
When one target dimension is blank, the calculator scales the ratio to find the missing side. When both dimensions are present, it compares the supplied frame with the selected ratio and reports the closest matching height and width for a quick production check.
Rounding controls how calculated dimensions are formatted. Use nearest values for most pixel-based layouts, round up when you need a minimum safe canvas size, round down when the result must not exceed a boundary, or exact decimal values for planning notes.
The tool does not crop, resize, or inspect files. It only calculates proportional dimensions from the numbers you enter. Your inputs stay in the browser, so no design specs, media dimensions, or planning notes are uploaded.
