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To simplify a ratio, divide both numbers by their greatest common divisor. 12:18 has a GCD of 6, so it simplifies to 2:3. Decimals are scaled up to whole numbers first. To solve A:B = C:D, cross-multiply: A × D = B × C, so D = B × C ÷ A.
Example: a recipe uses 2 cups of rice to 3 cups of water. For 10 cups of rice you need D = 3 × 10 ÷ 2 = 15 cups of water.
Find the greatest common divisor of both numbers and divide each by it. 45:60 → GCD 15 → 3:4.
Multiply both sides by the same number. 3:4 scaled by 5 gives 15:20. Use the solver above when you know one side of the new ratio.
Yes. 1.5:2.5 is the same as 15:25, which simplifies to 3:5.
No, everything is calculated in your browser.
See also: Percentage Calculator · Percent Change Calculator · Average Calculator