Aspect Ratio Calculator: a practical guide

When this is useful

An aspect ratio describes an image’s proportions rather than its file size or resolution. A 1920 by 1080 image and a 1280 by 720 image both have a 16:9 ratio. Matching ratios makes it easier to scale an image without stretching its subject.

A reliable workflow

Enter the original width and height as whole pixel counts. The tool divides both by their greatest common divisor to produce the simplified ratio. Enter a target width to calculate target height using original height multiplied by target width divided by original width.

Example input: 1920 × 1080

What to check before you finish

A calculated height may include a fraction, while an exported raster image needs whole pixels. Round for the actual resize and inspect the result. The calculator does not crop or enlarge an image by itself. Use the image resizer next with its aspect-ratio lock enabled, then compress the output if needed.

Keep the next step simple

Open the Aspect Ratio Calculator above to try the workflow. Your input is processed in your browser, without an account or file uploads. The related tools below can help with the next step; check the output before publishing it or adding it to a production system.