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Screen Aspect Ratio Finder

Find the aspect ratio (e.g., 16:9) of a resolution.

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Aspect Ratio

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Assumptions

  • Width and height should be positive whole-number dimensions.
  • The ratio is simplified using the greatest common divisor of the two dimensions.
  • The calculator reports the exact mathematical ratio, which may differ slightly from rounded marketing labels like 21:9.

Sensitivity preview

Width -10%: Aspect Ratio 8:5

Width Current: Aspect Ratio 16:9

Width +10%: Aspect Ratio 88:45

Formula: Divides Width and Height by their GCD (Greatest Common Divisor).

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About this Aspect Ratio

Aspect ratio describes the proportional relationship between the width and height of an image or screen. It is usually expressed as two numbers separated by a colon, like 16:9. This tool calculates the simplified ratio for any custom resolution.

Who this calculator is for

  • Editors, streamers, and designers checking whether footage or layouts match a target screen format.
  • Anyone comparing monitor, TV, projector, or phone resolutions.
  • Developers preparing assets for responsive or device-specific layouts.

When to use it

  • Use it to reduce a pixel resolution like 2560 x 1440 into its simplest display ratio.
  • Use it when checking if media fits 16:9, 4:3, ultrawide, or vertical video formats.
  • Use it before exporting graphics, slides, or videos for a specific platform.

How to use this calculator

  1. Enter the Width in pixels.
  2. Enter the Height in pixels.
  3. The tool calculates the simplest Aspect Ratio (e.g. 16:9).

Key assumptions

  • Width and height should be positive whole-number dimensions.
  • The ratio is simplified using the greatest common divisor of the two dimensions.
  • The calculator reports the exact mathematical ratio, which may differ slightly from rounded marketing labels like 21:9.

Accuracy and testing

Review formula sources, default test cases, assumptions, unit handling, rounding rules, and changelog for this calculator.

View accuracy page

How this calculator works

The calculator finds the Greatest Common Divisor (GCD) of the width and height, then divides both numbers by it to find the simplified ratio.
Divides Width and Height by their GCD (Greatest Common Divisor).

Inputs explained

Width/Height

The dimensions of the display or content in pixels.

Understanding your results

16:9 is standard for TV/YouTube. 4:3 is old TV/iPad. 21:9 is Ultrawide cinema. 9:16 is vertical mobile video.

Example scenarios

Full HD

1920 x 1080. GCD is 120. Ratio: 16:9.

Ultrawide

3440 x 1440. GCD is 40. Ratio: 43:18 (approx 21:9).

Key Features

  • GCD Logic
  • Supports any resolution
  • Instant simplification

Tips & Best Practices

  • Some modern phones have unusual ratios like 19.5:9 to accommodate notches.
  • Social media typically uses 1:1 (Square), 4:5 (Portrait), or 9:16 (Story).

Glossary of Terms

Aspect Ratio
The ratio of width to height.
GCD
Greatest Common Divisor. The largest positive integer that divides two numbers without a remainder.

Frequently Asked Questions

What is 16:9?
It is the international standard format of HDTV, non-HD digital television and analog widescreen television. Most computer monitors and TVs use this ratio.
Why is my ratio weird (e.g. 64:27)?
Ultrawide monitors (like 2560x1080) are often marketed as '21:9', but the mathematical ratio might be slightly different (64:27). The marketing term is an approximation.