Aspect Ratio Calculator
Reduce any width and height to a simple ratio, compare it with standard ratios such as 16:9 or 3:2, and calculate new dimensions without distortion.
Find the ratio of an image
Scale a size to a new ratio
Common print aspect ratios
| Ratio | Common print sizes |
|---|---|
| 3:2 | 4 × 6 in, 6 × 4 in photo prints |
| 5:4 | 8 × 10 in prints |
| 4:5 | 10 × 8 in portrait prints, Instagram portrait |
| 1:1 | Square prints and social posts |
| 2:3 | Posters such as 24 × 36 in |
How it works
The tool divides width and height by their greatest common divisor (GCD) to produce a simple ratio such as 16:9. To scale, it multiplies the known dimension by the ratio: if the width is known, height = width × (ratio height ÷ ratio width).
When to use this calculator
- Checking whether a photo will fit a print size without stretching or unwanted cropping.
- Resizing an image for the web while keeping the original proportions.
- Comparing a camera or screen ratio with standard formats such as 4 × 6 prints or 16:9 video.
- Working out the missing dimension when you know one side and the target ratio.
Worked examples
- 1920 × 1080 simplifies to 16:9, the standard widescreen and video ratio.
- 6000 × 4000 simplifies to 3:2, the classic 35 mm and 4 × 6 print ratio.
- 1200 px wide at 3:2 gives a height of 800 px - a common web image size.
- 3000 × 2400 simplifies to 5:4, which matches 8 × 10 prints.
Common ratios and where they are used
| Ratio | Typical use |
|---|---|
| 1:1 | Square social posts and albums |
| 3:2 | 35 mm photos, 4 × 6 prints |
| 4:5 | Portrait prints, Instagram portrait |
| 5:4 | 8 × 10 prints and frames |
| 16:9 | Video, monitors, wide banners |
| 2:3 | Posters such as 24 × 36 in |
Ratio is not resolution
The ratio describes the shape; resolution describes how many pixels make up that shape. A 1920 × 1080 video frame and a 3840 × 2160 monitor are both 16:9, but one has four times the pixels of the other. Use the megapixel calculator to compare pixel counts and the print size calculator to see how large each will print.
Common mistakes
- Resizing one dimension only, which stretches faces and circles into ovals.
- Confusing a ratio with a size: "16:9" says nothing about how many pixels or inches.
- Assuming every print size shares the same ratio - 8 × 10 (5:4) and 4 × 6 (3:2) do not.
- Rounding a ratio too early and accumulating errors across a resize.
Related tools
Photo crop calculator · Megapixel calculator · Print size calculator
Frequently asked questions
What does a 16:9 aspect ratio mean?
It means the width is 16 units for every 9 units of height, such as 1920 × 1080 or 3840 × 2160.
Will scaling change the quality of my image?
Scaling the canvas or cropping changes composition, not the source file. Upscaling pixels beyond the original resolution cannot add true detail and may look soft.