Aspect Ratio Calculator — 16:9 & More

Frequently asked questions

How is the ratio simplified?

The calculator divides both dimensions by their greatest common divisor, so 1920×1080 reduces to 16:9 and 1024×768 to 4:3. This mathematical simplification finds the smallest equivalent ratio, making it easy to understand the proportions at a glance. For example, 800×600 also simplifies to 4:3, confirming that these different pixel dimensions share the same aspect ratio. The simplified ratio is the one you'd use in design tools, video export settings, or when specifying responsive image dimensions.

Can I resize while keeping the same ratio?

Yes. Keep 'Lock aspect ratio' enabled and change either the width or the height; the other dimension updates automatically to preserve the proportions.

Is anything uploaded?

No. Everything runs locally in your browser using standard web APIs — your text, files and inputs are never uploaded to a server, so the tool works even offline once the page has loaded.

Pro tips

Lock the ratio and change one dimension when you need the other — this is the calculation people most often do wrong in their heads on a deadline.
Design with margin around the subject if the same asset has to work as 16:9, 1:1 and 9:16; a tightly framed composition has nothing to give when it is cropped square.
Check the ratio of an existing asset before matching to it, rather than assuming a standard — plenty of 'square' images are a few pixels off.
Remember that a ratio says nothing about resolution. 16:9 is equally true at 640×360 and 3840×2160, and only one of those will look sharp on a television.
When a platform states a ratio rather than pixel dimensions, pick the largest size in that ratio you can supply and let their pipeline downscale.

About Aspect Ratio Calculator

Ratios are reduced to their simplest whole-number form, so 1920 by 1080 reports as 16:9 rather than 1920:1080. Dimensions that reduce to something awkward like 137:96 are usually a sign the source was cropped rather than scaled.

An aspect ratio describes the proportional relationship between an image or screen's width and height, written as two numbers like 16:9. This calculator reduces any width×height to its simplest ratio, and — with the ratio locked — lets you change one dimension to instantly get the other, so you can resize without distortion.

It is the quick way to work out dimensions for a video export, a social banner, a print at a fixed proportion or a responsive layout. Common presets — 16:9, 4:3, 1:1 and more — are one click away, and locking one side gives you the other without arithmetic.

Ratios are how you keep a set of images consistent when their pixel sizes are not. Two photos at 1920×1080 and 1280×720 are different sizes and the same shape, so they crop, scale and sit in a grid identically. Reducing both to 16:9 is what makes that visible, and it is why the reduced form is more useful than the raw dimensions when you are planning a layout.

A ratio that reduces to something awkward is itself information. 1920×1080 gives a clean 16:9; a screenshot at 1912×1074 gives nothing recognisable, which usually means it was cropped by hand or captured with a window border included. If you are trying to match an existing set and the numbers refuse to simplify, the source is the problem rather than the arithmetic.

Common use cases

Video editors confirming an export matches the delivery spec before rendering a timeline that takes an hour.
Social media managers preparing one photo for a feed post, a story and a thumbnail, each of which wants a different shape.
Web developers reserving space for an embed so the page does not shift as the media loads.
Photographers deciding a print size that crops the least from a frame shot at 3:2.
Anyone scaling a design to a new canvas and needing the second dimension without reaching for a calculator.

How it comparesMost calculators in search results solve the same proportion and then bury it under an interstitial ad. The useful difference here is the reduced ratio shown alongside the resize, so you can see that 1920×1080 and your source are the same shape before committing to a size.