Design Tools
Aspect Ratio Calculator — Scale Dimensions & Calculate Ratios Free
Calculate the simplified aspect ratio of any width × height (e.g. 1920×1080 → 16:9), or scale dimensions proportionally by locking a target width or height. Includes one-click presets for 16:9, 4:3, 1:1, 21:9, 9:16, and 3:2.
How to use this tool
- Enter a width and height (or click a preset like 16:9 or 4:3).
- See the simplified ratio and optionally enter a new target width or height.
- Copy the scaled dimensions for use in your design or video project.
Common presets
Frequently Asked Questions
- How is the aspect ratio calculated?
- The width and height are divided by their greatest common divisor (GCD) to produce the simplest integer ratio. For example, 1920×1080 ÷ GCD(1920, 1080) = 1920÷120 × 1080÷120 = 16:9.
- What are common aspect ratios?
- 16:9 is the standard widescreen format for video and monitors. 4:3 is the older TV standard. 1:1 is square (Instagram). 21:9 is ultrawide. 9:16 is vertical video (mobile/Stories). 3:2 is the standard DSLR photo format.
- How do I scale an image while keeping its ratio?
- Enter the original width and height, then type a new target width in the Scale by Width field — the calculator outputs the proportional height. Or enter a target height to get the proportional width.
- Is this tool useful for video production?
- Yes — common uses include calculating safe zones for letterboxing/pillarboxing, scaling video assets to different resolutions while preserving the source ratio, and checking if a custom crop matches a target ratio before editing.