How to use this tool
Enter the original width and height, or choose a preset. To calculate a new size, choose which dimension you know and enter its value. Leave it blank to find only the ratio. Calculate, review any rounding, and copy the result.
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Aspect ratio calculator — find ratios and resize dimensions
Calculate an image or video aspect ratio, find a new width or height, and preview the proportions. Common presets, clear pixel rounding and copyable results. Free.
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Whole numbers from 1 to 1,000,000; Arabic and Persian digits are accepted. Use the same unit for both original dimensions. New dimensions are treated as pixels. The missing dimension rounds to the nearest whole pixel, with halves rounded up; a rounded value can change the ratio. Rounded outputs must be 1 to 1,000,000. This calculates dimensions; it does not resize or crop files. Inputs stay in your browser and are not saved.
Common aspect ratios
| Ratio | Example dimensions |
|---|---|
| 16:9 | 1920 × 1080 |
| 9:16 | 1080 × 1920 |
| 4:3 | 1024 × 768 |
| 3:2 | 1500 × 1000 |
| 1:1 | 1080 × 1080 |
| 4:5 | 1080 × 1350 |
Aspect ratio questions
How do I calculate an aspect ratio?
Divide width and height by their greatest common divisor. For 1920 × 1080, divide both by 120 to get 16:9. The order is always width first, then height.
How do I find a height from a width?
Multiply the new width by original height ÷ original width. At 16:9, a width of 1280 gives a height of 720. To find width instead, multiply the new height by original width ÷ original height.
Why does the result sometimes need rounding?
Pixel dimensions are whole numbers. A 16:9 image at width 100 has exact height 225/4, or 56.25 pixels. The nearest whole-pixel height is 56, which slightly changes the ratio. The calculator reports both the exact value and rounding.
Are 16:9 and 9:16 the same?
No. They are reciprocal proportions: 16:9 is wide and 9:16 is tall. Swap width and height to change orientation.
Does this crop or resize an image?
No. This tool plans dimensions and provides a ratio preview. Use the image resizer to export a resized file. Aspect ratio describes shape, not file size, image quality or print resolution.