Aspect Ratio Calc

Overview

Aspect ratio is the proportional relationship between an image's width and height, like 16:9 or 4:3. When you resize something, keeping that ratio constant is what stops it from looking stretched or squashed. This calculator finds the missing dimension when you change one side, simplifies any width×height into its ratio, and does it instantly in your browser without any upload.

How to Use (Step by Step)

1. 1

   Enter the original dimensions

   Type a width and height to define the starting aspect ratio.

2. 2

   Change one side

   Set a new width or height, and the tool calculates the matching dimension to keep the ratio.

3. 3

   Read the ratio or result

   See the simplified ratio and the resized dimension, ready to apply to your image or video.

How It Works

You enter an original width and height to establish the ratio, then change one dimension — the tool solves for the other so the proportion stays identical. It can also reduce a resolution like 1920×1080 to its simplest ratio (16:9) by dividing both numbers by their greatest common divisor. All the arithmetic runs locally, so nothing is sent anywhere.

When to Use This

Resizing an image or video to a new width while keeping it proportional. Finding the height for a given width at a target ratio like 16:9. Checking what ratio a resolution corresponds to. Preparing assets for a screen, print, or social format with a fixed ratio. Cropping to a standard ratio without distortion. Planning a responsive layout around a consistent proportion.

Frequently Asked Questions