Ratio Simplifier and Scaler

It finds the greatest common divisor (GCD) of the two numbers using Euclid's algorithm, then divides both sides by it. For 12:18 the GCD is 6, so the ratio reduces to 2:3.

It divides the first number by the second, so 1920:1080 reads as 1.777778. The value is rounded to six decimal places for display, and it is undefined whenever the second number is zero.

The ratio is reduced and the single minus sign is always moved onto the first number, so 4:-6 becomes -2:3. Two negatives cancel, meaning -4:-6 simplifies to a positive 2:3.

Yes. A zero on one side reduces to 0:1 or 1:0, and 0:0 is returned unchanged. When the second side is zero the decimal is reported as undefined because you cannot divide by zero.

It multiplies both sides of the already-simplified ratio by the factor you type, keeping the proportion identical. So 16:9 scaled by 2 becomes 32:18, and scaling by 0.5 would give 8:4.5.

The two ratio inputs expect whole numbers, and a non-integer shows an 'Enter whole numbers' message. The Scale by field is the only place a decimal factor is allowed.

The math overlaps, since 1920:1080 reducing to 16:9 is exactly an aspect ratio. This tool is more general, though, working for any two quantities such as ingredients, gear teeth or mixing parts.

Scaling multiplies literally, so a fractional factor can produce fractional sides. That is expected: 16:9 scaled by 1.5 is 24:13.5, which is left as-is rather than re-rounded.

Yes. All of the arithmetic happens inside your browser and none of the numbers you enter are sent anywhere.