Aspect Ratio Calculator
Enter an image or video ratio and one known dimension. The calculator finds the matching width or height in pixels so the proportions stay unchanged.
How to find the right image dimensions
- Select a common ratio or enter the ratio width and height yourself.
- Enter the pixel width you already know and choose Calculate height, or enter the height and choose Calculate width.
- Use the matching dimensions when resizing or creating the image. Results are rounded to whole pixels.
What is an aspect ratio?
An aspect ratio compares width with height; it is not the same as resolution. A 16:9 image could be 1920 × 1080, 1280 × 720 or 640 × 360. Those images have different pixel counts but the same shape. A 1:1 ratio is square, while 9:16 is a tall vertical frame.
Aspect ratio formulas
To calculate height, use height = width × ratio height ÷ ratio width. To calculate width, use width = height × ratio width ÷ ratio height. For example, a 16:9 image that is 1200 pixels wide is 675 pixels high.
Common image and video ratios
| Ratio | Shape | Example dimensions |
|---|---|---|
| 1:1 | Square | 1080 × 1080 |
| 4:3 | Traditional photo/display | 1600 × 1200 |
| 3:2 | Common camera photo | 1800 × 1200 |
| 16:9 | Widescreen landscape | 1920 × 1080 |
| 9:16 | Vertical video | 1080 × 1920 |
Resize, crop or compress?
Resizing changes the pixel dimensions. Keeping the same ratio avoids distortion. Cropping removes parts of an image so it can fit a different shape. Compression targets file size and may leave width and height unchanged. If you need to inspect an existing file first, use the Image Dimensions Checker.
Related image tools and guides
Resize an image • Crop an image • Create a social image size • Read the aspect ratio guide • Choose image sizes for websites
Frequently asked questions
Will this calculator upload my image?
No image is needed. It calculates dimensions from the numbers entered in your browser.
Why is the result rounded?
Raster image dimensions use whole pixels. Rounding by one pixel is normally necessary when a calculation produces a fraction.