Find the simplified ratio for any dimensions, or calculate the matching width/height for a target ratio. Common presets included.
This calculator finds the simplified aspect ratio for any pair of dimensions (such as 1920×1080 simplifying to 16:9), and works in reverse — given a target ratio and one dimension, it calculates the matching second dimension. Common presets for popular ratios are included for quick reference.
Aspect ratio describes the proportional relationship between an image or video's width and height. Getting it right matters because many platforms and displays expect specific ratios — a video uploaded with the wrong ratio may display with unwanted black bars (letterboxing) or get cropped; an image resized to fit a frame with a different ratio than the original will either be cropped or stretched. Knowing the ratio of your current dimensions, and what dimensions match a target ratio, helps you plan resizing and cropping correctly before you start.
It's easy to assume "16:9" or "1:1" refers to one specific size, but aspect ratio is purely about proportion — many different pixel dimensions share the same ratio. A 1920×1080 video and a 1280×720 video are both 16:9, just at different resolutions; similarly, a 1000×1000 image and a 3000×3000 image are both 1:1. This matters when planning a project: if you're told a platform "requires 16:9," that doesn't specify an exact resolution, only a proportion — you can typically choose any resolution that maintains that ratio, with higher resolutions giving more detail at the cost of larger file sizes.
A common scenario: you have an image at one resolution (say, a 4000×3000 photo from a camera, which is 4:3) and need to crop it to a different ratio (say, 1:1 for a square social media post) without distorting it. The calculator helps here by letting you work out, for your image's shorter dimension, what the corresponding dimension would be at your target ratio — for a 4000×3000 image cropped to 1:1, you'd crop to 3000×3000 (using the shorter side as the basis), removing 1000px total from the width. Knowing these target dimensions in advance makes it much easier to position a crop accurately rather than cropping by eye and checking afterward.
Aspect ratio calculations work the same whether you're planning for screens or print, but the "common ratios" differ. Standard print photo sizes (like 4×6 inches, 5×7 inches, or 8×10 inches) don't always match screen-oriented ratios like 16:9 or 1:1 — a 4×6 inch print is a 2:3 ratio, which is close to but not the same as the 3:2 ratio of most digital camera photos straight out of the camera. This is why printing a digital photo at certain sizes sometimes results in a small amount being cropped from one edge — the camera's native ratio doesn't perfectly match the print size's ratio. Using this calculator to check both your image's current ratio and your target print size's ratio ahead of time can help you anticipate and control any cropping, rather than being surprised by it after printing.
Once you know the dimensions you need, our Image Resizer can resize an image to those exact dimensions, or our Image Cropper can crop to a specific ratio directly using built-in presets for common ratios like 1:1, 16:9 and 4:3.
The calculator finds the greatest common divisor of the width and height and divides both by it, producing the simplest whole-number ratio that represents the same proportions.
Yes, you can enter any ratio (such as 5:4 or 2.35:1) along with a known dimension to calculate the matching dimension.
You'll need to either crop the image to the target ratio using Image Cropper, or resize it (which may distort proportions unless cropped first).
No, this is a calculator only. For actually resizing or cropping images, use Image Resizer or Image Cropper.
No, any positive numbers can be entered for width, height or ratio values.