Aspect Ratio Calculator
Simplify ratios and find missing dimensions.
How to use
- 1 To simplify, enter a width and height and read the reduced ratio.
- 2 To find a dimension, set the ratio width and height (e.g. 16 and 9).
- 3 Choose whether you know the width or the height, and enter it.
- 4 Read the computed dimensions and copy any result.
About Aspect Ratio Calculator
The Aspect Ratio Calculator does two related jobs.
First, it reduces a pair of dimensions to its simplest ratio: feed it 1920 by 1080 and it returns 16:9, or 1280 by 1024 and it returns 5:4, by dividing both sides by their greatest common divisor.
Second, it finds a missing dimension — give it a target ratio such as 16:9 and a width of 1920, and it calculates the matching height of 1080.
Aspect ratios are everywhere in screens, photos, video and design.
You might need to know whether an image is widescreen, resize a video to fit a 4:3 frame without distortion, or work out the height of a responsive embed at a given width.
Doing this by hand means remembering to reduce fractions and cross-multiply correctly; getting it slightly wrong leaves you with stretched or letterboxed content.
Both tools update instantly as you type and validate their inputs, so you get a clear error instead of a nonsensical result when a value is zero or negative.
The simplify tool expects whole-number dimensions, while the missing-dimension tool accepts decimal ratios and sizes.
As with every My Tools Garage utility the maths is a pure client-side function — nothing is uploaded, nothing is tracked, and it works offline.
It is a quick, dependable companion whenever pixels and proportions need to line up.
FAQ
How does it simplify a ratio?
It divides the width and height by their greatest common divisor, so 1920×1080 reduces to 16:9.
Can I use it to resize without distortion?
Yes. Enter the target ratio and the dimension you know, and it gives the other dimension that preserves the ratio.
Does it accept non-whole numbers?
The simplify tool needs whole-number dimensions; the missing-dimension tool accepts decimal ratios and sizes.