What does aspect ratio mean here?

Aspect ratio is the relationship between width and height. A frame that is 1920 by 1080 has a 16:9 ratio, which means every resize has to keep the same proportion if you want the image or video to stay undistorted.

Why does the other side change automatically?

Because only one target side should drive the resize at a time. When you lock a new width, the matching height is width divided by the source ratio. When you lock a new height, the matching width is height multiplied by the source ratio.

Why might I see an exact ratio like 683:384 plus an approximate 16:9 hint?

Some real source sizes reduce to awkward but perfectly correct integer ratios. The calculator keeps the true reduced ratio visible, then adds a nearby common-ratio hint only as a reference. It never snaps your media to that hint.

How is this different from the Screen Size calculator?

Screen Size starts with a display diagonal and an aspect ratio, then solves for width and height. This calculator starts with a real width and height that already exist and helps you resize the media without changing its shape.

GEOGeometry

Aspect Ratio Calculator

Resize media without distortion. Enter the original width and height once, then set either a new width or a new height and the matching side is recalculated instantly. This page is for preserving a photo or video frame while scaling it, not for turning a screen diagonal into dimensions like the Screen Size calculator.

Original width

Original height

New width(optional)

New height(optional)

Try an example

Enter values above to see results

How It Works

Formula

R = \dfrac{W_1}{H_1}

H_2 = \dfrac{W_2}{R}

W_2 = H_2 \times R

Where

$W_1$: Original width(px)
$H_1$: Original height(px)
$W_2$: New width(px)
$H_2$: New height(px)
$R$: Source aspect ratio (original width divided by original height)

The calculator first reads the source ratio as width divided by height. Then it treats either the new width or the new height as the driver and recomputes the other side so the ratio stays unchanged.

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