Ratio Calculator
Simplify a ratio to lowest terms, split a total by a ratio, or solve A : B = C : D for one missing value.
Simplify a ratio
Use positive values with up to 6 decimal places.
Split a total by ratio
Solve A : B = C : D
Leave exactly one of A, B, C or D blank. Use positive values for the other three.
How to use the ratio calculator
Choose the calculation that matches your problem. Simplify reduces a ratio such as 24 : 36 to its lowest terms. Split total divides an amount using a ratio such as 2 : 3. Solve proportion finds the one missing value in A : B = C : D.
Enter your known values and select Calculate. The result includes the formula so you can check the calculation yourself.
Simplify a ratio
Reduce two values to the smallest equivalent whole-number ratio. For example, 24 : 36 simplifies to 2 : 3 by dividing both values by 12.
Solve a missing ratio value
Enter three values in A : B = C : D and leave exactly one box blank. The calculator uses cross multiplication, where A × D = B × C, to find the missing value.
Split a total by ratio
Divide a total into proportional shares. A total of 100 split in the ratio 2 : 3 gives 40 and 60 because the ratio contains five equal parts.
Worked ratio examples
Simplify decimals: 1.5 : 2.25 becomes 2 : 3. Multiply both values by 100 to get 150 : 225, then divide by the greatest common divisor, 75.
Share a total: To split 250 in the ratio 2 : 3, first add the parts (2 + 3 = 5). One part is 250 ÷ 5 = 50, so the shares are 100 and 150.
Find a missing number: For 2 : 3 = 10 : x, cross-multiply to get 2x = 30, so x = 15. Use the Solve proportion tab above to check your result.
Need percentage change instead? Try the Percentage Calculator. Splitting a bill equally, with tips or rounding? Use the Tip Calculator & Bill Splitter.
Ratio Calculator FAQ
How do you simplify a ratio?
Divide both values by their greatest common divisor. For example, 12 : 18 becomes 2 : 3 after both values are divided by 6.
How do you solve A : B = C : D?
Use cross multiplication: A × D = B × C. Enter three known values and leave one field blank, and the calculator solves the missing value.
How do you split a total by a ratio?
Add the ratio parts, divide the total by that sum, then multiply by each ratio part. For a 3 : 2 split of 25, the shares are 15 and 10.
Can I simplify a ratio with decimals?
Yes. The calculator supports positive decimal values with up to six decimal places and converts them to an equivalent simplified ratio.
What are equivalent ratios?
Equivalent ratios describe the same relationship using different values. For example, 2 : 3, 4 : 6 and 8 : 12 are equivalent ratios.