Aspect Ratio Calculator

Aspect Ratio Calculator

An aspect ratio compares the width of something to its height. 1920 × 1080 reduces to 16:9, 1600 × 900 does too, and so does any pair you can divide by the same number. This calculator does that reduction for you and works in the other direction as well: keep a proportion and solve for the side you do not know yet. Everything happens on your device, and no value ever leaves it.

What you can do

• Simplify a size into a ratio — enter a width and height to get the simplest form (1366 × 768 becomes 683:384, not a guessed 16:9), the decimal value, and whether the shape is square, landscape or portrait.
• Use a common ratio quickly — the preset buttons 16:9, 4:3, 3:2, 1:1, 21:9, 9:16 and 2:3 fill both sections at once.
• Compute the missing side — with a ratio such as 16:9, 16/9 or 1.85, type the width or the height you already know and read the other one. A note appears when the answer is not a whole number, so you can decide how to round for pixel work.
• See the proportion — the preview draws the resolved shape box, which is useful when the numbers alone do not tell you what a 21:9 frame looks like.

Ratios you will meet often

How the numbers are kept honest

Ratios are reduced by their greatest common divisor, and decimal sizes are scaled first so 1.85:1 becomes 37:20. Nothing is guessed or snapped to a famous ratio: if a size does not divide cleanly, the exact reduction is shown together with its decimal value. Zero, blank or negative input is reported instead of producing a result.

Typical jobs

• Picking a canvas or crop size and checking what it resolves to.
• Keeping a UI mockup in proportion while one side changes.
• Scaling a video, image or background gradient between two sizes.