What is an aspect ratio?

An aspect ratio is the proportional relationship between the width and height of an image, video, or screen. It is expressed as two numbers separated by a colon, like 16:9 or 4:3.

How do I calculate the aspect ratio from pixel dimensions?

Enter your width and height into the calculator. It divides both values by their greatest common divisor (GCD) to give you the simplified ratio. For example, 1920×1080 simplifies to 16:9.

What are common aspect ratios?

16:9 (widescreen video, most monitors), 4:3 (classic TV and presentations), 1:1 (square, Instagram posts), 9:16 (vertical video, Stories/Reels), 21:9 (ultrawide cinema), and 3:2 (DSLR photos).

Can I lock a ratio and compute missing dimensions?

Yes. Select or calculate a ratio, click the lock icon, then type either width or height. The other dimension updates automatically while maintaining the locked ratio.

Free & No Signup

Calculate & Visualize
Aspect Ratios

Enter width × height to get the simplified ratio. Lock a ratio to auto-compute the missing dimension. See a live preview — all in your browser, no backend needed.

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Instant Calculation

Type any width and height to instantly see the simplified aspect ratio.

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Lock & Resize

Lock a ratio, change one dimension, and the other updates automatically.

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Live Preview

See a scaled visual box that matches your aspect ratio in real time.

Common Presets

Width

Height

Aspect Ratio

16:9

Decimal

1.7778

CSS aspect-ratio

16 / 9

Pixels

1920 × 1080 px

Live Preview

16:9

1920×1080 → 16:9

Frequently Asked Questions

Everything you need to know about Aspect Ratio Calculator.

Calculate & VisualizeAspect Ratios

Instant Calculation

Lock & Resize

Live Preview

Common Presets

Frequently Asked Questions

Calculate & Visualize
Aspect Ratios