Aspect Ratio Calculator

An aspect ratio describes the proportional relationship between a shape's width and height, written as two numbers separated by a colon — 16:9, 4:3, 1:1. It doesn't matter whether the shape is a photo, a video frame, a browser window, or a print poster: the ratio stays the same as long as width and height scale together. A 1920x1080 monitor and a 320x180 thumbnail are both "16:9" because they reduce to the same two numbers.

This calculator does two things with that idea, and you can use either one independently:

1. Simplify a pixel size into its ratio. Enter a Width and a Height (say, 3840 and 2160) and the tool reduces them to the smallest whole-number ratio — 16:9 — using the Euclidean algorithm to find the greatest common divisor (GCD) of the two numbers. This is exact integer math, not a rounded approximation, so the result is always the true simplified ratio. You also get the decimal form of the ratio (width ÷ height), the orientation (Landscape, Portrait, or Square), and a match against common named ratios like 16:9 widescreen or 3:2 classic photo, when your pair lines up with one.

2. Solve a missing dimension from a known ratio. Know you want a 16:9 frame and already have a width of 1280px, but need the matching height? Fill in Ratio width (16) and Ratio height (9) plus just the Width field, leave Height blank, and the calculator cross-multiplies to find the missing side: height = width x ratioHeight / ratioWidth = 720px. Works in either direction — give it a known Height instead and it solves for Width the same way.

How to use it

1. To simplify a size: enter both Width and Height, leave the ratio fields blank.
2. To solve a missing side: enter Ratio width and Ratio height, then fill in exactly one of Width or Height (leave the other blank).
3. Results update automatically in the table — Simplified Ratio, Decimal Ratio, Orientation, Solved Width, Solved Height, and a Common Preset Match if your ratio matches a well-known one.

FAQ

Why does 1920x1080 simplify to 16:9 and not something else? Because the greatest common divisor of 1920 and 1080 is 120. Dividing both numbers by 120 gives 16 and 9 — the smallest whole-number pair with the same proportions. Any resolution sharing that same GCD-reduced pair (1280x720, 2560x1440, 3840x2160) is also "16:9."

Common aspect ratios and where you'll see them:

Ratio	Typical use
1:1	Square social posts, profile photos
4:3	Older TVs and monitors, classic slide decks
3:2	Classic 35mm photography
16:9	HD/4K video, widescreen monitors
16:10	Some laptop and tablet screens
21:9	Ultrawide monitors, cinematic video
9:16	Phone screens, Reels/Stories/Shorts

What if I enter a width and height that don't reduce to a "nice" ratio? That's fine — most real-world dimensions won't match a named preset. You'll still get the exact simplified ratio and decimal value; the "Common Preset Match" column just shows "-" when there's no well-known match.

Can I solve for a dimension using an already-simplified ratio, like 16:9 directly? Yes — the ratio fields don't need to be in lowest terms, but using the reduced form (16 and 9, not 1920 and 1080) keeps the numbers easy to read.

Is my data uploaded anywhere? No. All calculations run locally in your browser (or, if you call the API, entirely server-side per request) — nothing is stored or logged.