Image Aspect Ratio Calculator
Enter width and height to find the aspect ratio, simplified fraction, decimal, and orientation. Scale to any size while keeping proportions.
Quick pick
Scale to new size
Crop to target ratio
How to Calculate Image Aspect Ratio
An aspect ratio expresses the proportional relationship between width and height as two numbers separated by a colon โ for example 16:9 or 4:3. To calculate it, divide both dimensions by their greatest common divisor (GCD). For a 1920ร1080 image the GCD is 120, giving 16:9.
Common Aspect Ratios
| Ratio | Decimal | Typical use |
|---|---|---|
| 1:1 | 1.00 | Instagram square, profile pictures |
| 4:3 | 1.33 | Standard SD video, older monitors |
| 3:2 | 1.50 | 35 mm photography, DSLR sensors |
| 16:9 | 1.78 | HD/4K video, widescreen monitors, YouTube |
| 21:9 | 2.33 | Ultrawide cinema, gaming monitors |
| 9:16 | 0.56 | TikTok, Instagram Stories, mobile video |
| 2:3 | 0.67 | Portrait photography prints |
| 5:4 | 1.25 | Large-format photography, older LCD displays |
Scale While Keeping Ratio
Use the Scale to new size fields to find the matching dimension for a given width or height. For example: you know your target width is 800 px and you want the correct height for a 16:9 image โ enter 800, click "Get Height", and the tool returns 450 px.
Crop to a Target Ratio
The Crop to target ratio field calculates the largest area you can crop from the current image dimensions to fit a specific ratio without scaling up. It also shows what percentage of the original area is preserved.
Related Image Tools
Formula
GCD(w, h) โ greatest common divisor
Ratio = w/GCD : h/GCD
Decimal = w รท h