Aspect Ratio Calculator

Calculate aspect ratios from dimensions or find missing width/height from a target ratio.

aspect_ratioAspect Ratio Calculator

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Settings

Mode

Width (px)

Height (px)

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Results

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Enter dimensions or a ratio to see results

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About Aspect Ratio Calculator

The Aspect Ratio Calculator helps you determine the proportional relationship between the width and height of an image, video, or screen. Enter any width and height to instantly find the simplified ratio (e.g., 16:9), or provide a target ratio and one dimension to calculate the missing side. It is essential for designers, video editors, and developers who need to maintain correct proportions when resizing or cropping media.

Aspect ratios are fundamental in photography, cinematography, web design, and display technology. Common ratios include 16:9 for widescreen video, 4:3 for classic TV and presentations, 1:1 for social media squares, and 21:9 for ultrawide monitors. All calculations run locally in your browser with no data sent to any server.

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How to Use

Choose a Mode

Select "Calculate Ratio" to find the ratio from width and height, or "Calculate Dimension" to find a missing dimension from a known ratio.

Enter Values

In Ratio mode, enter the width and height in pixels. In Dimension mode, pick a preset ratio or type custom ratio values, then enter the known width or height.

View Results

The calculator instantly displays the simplified aspect ratio, decimal ratio, dimensions, and a proportional visual preview.

Check Common Resolutions

If your ratio matches a standard (16:9, 4:3, etc.), a table of common resolutions for that ratio is shown for quick reference.

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Frequently Asked Questions

What is an aspect ratio? expand_more

An aspect ratio is the proportional relationship between the width and height of a rectangle. It is expressed as two numbers separated by a colon, such as 16:9. A 16:9 ratio means the width is 16 units for every 9 units of height, regardless of the actual size.

How is the aspect ratio calculated from dimensions? expand_more

The calculator finds the greatest common divisor (GCD) of the width and height, then divides both values by the GCD. For example, 1920 and 1080 have a GCD of 120, so 1920/120 = 16 and 1080/120 = 9, giving a 16:9 ratio.

What is the most common aspect ratio for video? expand_more

16:9 is the most widely used aspect ratio for video content, including YouTube, Netflix, and broadcast television. It is the standard for Full HD (1920x1080), QHD (2560x1440), and 4K UHD (3840x2160) resolutions.

How do I calculate a missing dimension from a ratio? expand_more

Switch to "Calculate Dimension" mode, enter or select your target ratio (e.g., 16:9), choose whether you know the width or height, and enter that value. The calculator multiplies by the ratio to find the other dimension. For example, with a 16:9 ratio and width of 1920, the height is 1920 x (9/16) = 1080.

Is my data secure when using this calculator? expand_more

Yes. All calculations happen locally in your browser using JavaScript. No dimensions, ratios, or other data are sent to any server. The tool works fully offline once loaded.