How is this different from just dividing width by height?

Dividing gives a single decimal number (like 1.7778), useful for comparison, but the simplified whole-number ratio (16:9) is what's conventionally used to name and describe standard formats.

Can I use this for print dimensions instead of pixels?

Yes — the ratio math is unitless, so it works identically whether your width and height are in pixels, inches, centimeters, or any other consistent unit.

What if I want to scale by height instead of width?

Enter the new value in the 'scale to a new width' field using whichever dimension you're targeting — since it's a straight ratio, you can treat the labeled 'width' field as whichever dimension you actually want to fix, and read the other one from the result.

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Converters

Aspect Ratio Calculator

Simplify a ratio, or scale a dimension to match it.

🔒 Runs entirely in your browser — nothing here is ever uploaded

About the Aspect Ratio Calculator

Simplifies a width/height pair into its lowest-terms ratio (like 1920×1080 → 16:9), and scales a dimension to a new size while preserving that exact ratio.

How to use it

Enter a Width and Height.
Read the simplified ratio and decimal ratio in the result panel.
Enter a new Width to see the matching Height that preserves the same ratio.

Formula

Simplified ratio = width ÷ GCD(width, height) : height ÷ GCD(width, height), where GCD is the greatest common divisor of the two values (computed via the Euclidean algorithm)
Scaled height = (new width × original height) ÷ original width

Worked example

1920×1080 simplifies to a 16:9 ratio (1.7778:1) — scaling to a new width of 1280px keeps that exact ratio at 720px tall, the standard 720p resolution.

Recommendations

• Common video/display ratios are recognizable once simplified — 16:9 (widescreen), 4:3 (older TVs/monitors), 21:9 (ultrawide), and 1:1 (square) are the ones you'll see most often.
• The GCD-based simplification is exact — no rounding — so the simplified ratio always represents the original dimensions precisely, unlike a decimal approximation.
• For print or physical media, the same ratio math applies regardless of unit (inches, cm, pixels) — the ratio itself is unitless.

Frequently asked questions

Not every real-world image or video has been shot or cropped to a standard ratio — the simplified result is mathematically exact for whatever dimensions you entered, even if it doesn't match a common named ratio.