Aspect Ratio Calculator takes any width and height, simplifies the ratio (e.g. 1920×1080 → 16:9), shows the decimal ratio, and provides a scaling tool where you enter one dimension and get the other. Common presets (16:9, 4:3, 1:1, 21:9, 3:2) are available as quick buttons.
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The tool uses the GCD (greatest common divisor) algorithm to reduce both dimensions to their smallest integer ratio. For example, 1920×1080 reduces to 16:9 because GCD(1920,1080) = 120.
Yes. The scaling tool is useful for both screen (video, web) and print dimensions. Enter your known dimension and get the proportionally correct counterpart, though print work should also account for DPI/resolution separately.
Enter a width and it calculates the height that preserves your current aspect ratio, or enter a height and it calculates the matching width. Entering one field clears the other so you always get a fresh calculated value.
The presets fill in real, commonly used resolutions so you get both the simplified ratio and a sense of a practical dimension pair — you can then use the Scale tool to resize proportionally from there.
The decimal ratio (e.g. 1.7778 for 16:9) is what's actually used internally for scaling calculations, and it's useful when comparing two ratios that don't reduce to clean whole numbers, like 1.91:1 for some social media formats.
Yes, the width and height fields accept decimal values, and the ratio simplification rounds them to the nearest whole number first before computing the GCD.
Aspect ratios matter for responsive image containers (using CSS aspect-ratio), print layouts, social media image specs, and UI component sizing where a consistent visual proportion needs to be preserved across different sizes.
