Gypes

Image and video tool

Aspect ratio calculator

Reduce source dimensions to a ratio and calculate a matching height at a new width.

How an aspect ratio is simplified

Divide width and height by their greatest common divisor. For 1,920 × 1,080 pixels, the greatest common divisor is 120, giving the familiar 16:9 ratio.

Proportional resizing

To keep the original proportions, multiply the new width by source height divided by source width. A 16:9 image resized to 1,280 pixels wide is 720 pixels high.

Rounding pixel dimensions

A proportional calculation can produce a fractional pixel. Raster output normally requires whole pixels, so choose an appropriate rounding direction and confirm the encoder, layout, or platform requirements. A one-pixel difference can slightly change the exact ratio.

This tool calculates geometry only. It does not crop, resize, compress, or upload an image, and it does not account for pixel aspect ratios other than square pixels.