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Calculate simplified and decimal aspect ratios from width and height, and scale dimensions while preserving the ratio
Aspect Ratio Calculator is loading — interactive editor will appear here. Use examples below to try instantly once loaded.
Press ? for keyboard shortcuts
Calculates the aspect ratio of any width and height pair. It shows the simplified integer ratio (using the greatest common divisor, so 1920x1080 becomes 16:9) and the decimal ratio, plus a scale calculator: enter a target width to get the matching height, or a target height to get the matching width, with the ratio preserved exactly. One-click presets cover 16:9, 4:3, 1:1, 9:16, 21:9, and 3:2.
Resizing images and videos without distorting them means keeping the aspect ratio constant, and doing that math by hand (or with a generic calculator) is error-prone. This tool turns 'what height matches 800px wide at 16:9?' into an instant answer.
This tool is part of the DevStackIO platform — a collection of free online developer tools from DevStackIO. Browse more free developer resources on DevStackIO.
Web and app developers sizing images and embeds, designers preparing assets for multiple screen sizes, video editors matching footage to deliverable formats, and social media managers cropping to platform ratios.
Enter the width and height in pixels (or any matching unit) in the first two fields
Read the simplified ratio (e.g. 16:9) and the decimal value (e.g. 1.7778) in the result panel
Optionally click a preset such as 16:9 or 1:1 to fill the dimensions instantly
Enter a target width under 'Scale to width' to get the matching height
Or enter a target height under 'Scale to height' to get the matching width
Use the computed dimensions in your editor, CSS, or export dialog
Input: width 1920, height 1080. Output: ratio 16:9, decimal 1.7778; at width 800 the height is 450.Input: preset 9:16 (1080x1920). Output: ratio 9:16, decimal 0.5625 — the vertical-video equivalent of widescreen.How is the simplified ratio computed?
The tool divides both dimensions by their greatest common divisor, so 1920:1080 reduces to 16:9 and 2560:1080 to 64:27.
What is the decimal ratio?
It is width divided by height. 16:9 equals about 1.7778; values below 1 mean the image is taller than it is wide.
Does the tool work for print sizes? Yes
any matching unit works (pixels, cm, inches), as long as both dimensions use the same unit.
Is any data sent to a server?
No. The calculation is plain integer math that runs entirely in your browser.
Authoritative specifications, standards, and in-depth reading for Aspect Ratio Calculator.
Preset ratios
Aspect ratio
16:9
Decimal
1.7778
Dimensions
1920 by 1080 pixels
At width 800px → height 450px (800×450)
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