Ratio Calculator
Solve ratios A : B = C : D, simplify a ratio to its lowest terms, or divide an amount in a given ratio — with every step shown.
Leave the value you want to find empty.
Solving a proportion A : B = C : D
Two equal ratios form a proportion. Cross-multiplying gives A × D = B × C, so any one missing value can be found from the other three. Leave the unknown box empty.
Example: 3 : 4 = 15 : D gives D = 4 × 15 ÷ 3 = 20.
Simplifying a ratio
Divide every part by their greatest common factor. 24 : 36 has a GCF of 12, so it simplifies to 2 : 3. Decimals are first multiplied to whole numbers: 1.5 : 2.5 : 4 becomes 15 : 25 : 40 and then 3 : 5 : 8. The calculator also shows the 1 : n form and each part’s share in percent.
Dividing an amount in a ratio
Add the parts, divide the amount by the total to get one part, and multiply. 1,000 in the ratio 2 : 3: one part is 1,000 ÷ 5 = 200, so the shares are 400 and 600.
Frequently asked questions
How do you solve a ratio with a missing number?
Cross-multiply. For 3 : 4 = 15 : x, 3 × x = 4 × 15, so x = 20.
How do I simplify a ratio?
Divide all parts by their greatest common factor: 24 : 36 ÷ 12 = 2 : 3.
How do I split money in a ratio?
Divide the amount by the sum of the parts, then multiply by each part. 1,000 in 2 : 3 gives 400 and 600.