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Aspect Ratio & Resolution Calculator
Simplify any width and height to a ratio and scale dimensions without distortion.
Find the ratio
Scale to a new size
About this tool
Resizing an image, video or screen design without stretching it requires keeping the aspect ratio constant. The aspect ratio is the proportional relationship between width and height, written as two numbers such as 16:9 or 4:3. This calculator does both directions of the job.
First, enter a width and height to reduce them to the simplest ratio using the greatest common divisor, along with the decimal ratio and the total megapixels. Second, enter a target ratio and one known dimension, and the tool computes the missing one, rounded to the nearest pixel. A list of presets covers the formats designers use every day: 16:9 for HD video, 9:16 for vertical stories and reels, 1:1 for square posts, 4:3 and 3:2 for photography, 21:9 for ultra-wide monitors and 2:3 for portrait prints.
Because the calculation is pure arithmetic, the result is instant and nothing is uploaded.
How to use it
- Enter the original width and height to see the simplified ratio.
- Choose a preset or type your own ratio, then enter either the new width or the new height.
- Use the calculated dimension in your editor, CSS or export settings.
Frequently asked questions
What is the aspect ratio of 1920x1080?
16:9.
Why is the result rounded?
Pixels are whole numbers, so the computed dimension is rounded to the nearest pixel, which can introduce a tiny difference in ratio.
What ratio should I use for YouTube Shorts and Reels?
9:16, for example 1080 x 1920 pixels.
Results are provided for general information. Please read our disclaimer.