Aspect Ratio Calculator

How to use it: enter any source width and height to simplify the ratio, then enter a target width to calculate the matching height without stretching.

Formula. Divide width and height by their greatest common divisor. Target height = target width x source height / source width.

Example. 3840 x 2160 simplifies to 16:9; at 1920 pixels wide the matching height is 1080 pixels.

The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.

Source width

3840 px

Source height

2160 px

Target width

1920 px

Primary result: Simplified ratio: 16:9.

• Measure from the datum or reference edge described by this tool, and do not mix inside, outside and centerline dimensions.
• Keep inputs in the displayed units and preserve more precision than the final cutting or purchasing tolerance requires.
• When the result is close to a limit, verify it with a test piece, field measurement, manufacturer drawing or qualified project professional.

This preserves geometry only. It does not crop, resize or inspect a media file, and it does not account for non-square pixels or anamorphic signaling.