Image Aspect Ratio Calculator
Use this image aspect ratio calculator to find the ratio of a photo, design or graphic from its pixel dimensions. Enter the width and height, or use RatioForge’s local image reader, then calculate the simplified ratio and matching resize dimensions without distorting the image.
Image ratio calculator
Common image ratios
| Size / ratio | Label | Use-case |
|---|---|---|
| 1080×1080 | 1:1 | Square social post or avatar |
| 1080×1350 | 4:5 | Instagram portrait image |
| 1200×630 | 1.91:1 | Link preview image |
| 1920×1080 | 16:9 | Web hero or video still |
| 4000×3000 | 4:3 | Common camera/photo shape |
Image ratio formula
Simplify image ratio: divide width and height by their greatest common divisorResize by width: new height = new width × original height ÷ original widthResize by height: new width = new height × original width ÷ original height.
How to use image ratios before resizing
Images often need to move between platforms: a camera photo, a website hero, an Instagram crop and a link preview can all require different shapes. Calculating the ratio first tells you whether a resize will preserve the whole image or whether a crop is unavoidable.
RatioForge reads a dropped image locally: it measures the pixel dimensions in your browser and does not upload the file. That makes the tool more trustworthy than generic upload-based resizers.
Start with diagnosis before resizing. You often know you have a file but not whether it is 4:3, 3:2, 16:9 or something unusual. Enter the pixel width and height to identify the shape before choosing a crop — useful for photographers, bloggers, ecommerce sellers and designers preparing assets for multiple placements.
The privacy angle matters: because the dimension reader runs in your browser, private files stay on your device. Once you know the source shape, turn it into a platform-ready crop with the 4:5 or 1:1 calculator, or read the math step by step in how to calculate an aspect ratio.
Frequently asked questions
Related calculators and guides
- Aspect ratio calculator — the main calculator with custom ratios
- 4:5 aspect ratio calculator — portrait crops for the feed
- 1:1 aspect ratio calculator — square crops for avatars and posts
- How to calculate an aspect ratio — the math, step by step
- Aspect ratios explained — what the common ratios mean