How do you simplify a ratio?

Divide both numbers by their greatest common divisor. For 1920:1080 the GCD is 120, giving 16:9. The tool does this automatically.

Can it solve for a missing number in a proportion?

Yes. Enter three of the four values in the A:B = C:D form and leave one blank — the calculator cross-multiplies to find it.

CalculatorsRuns in your browser

Ratio Calculator

Simplify ratios to their lowest terms, scale them up or down, and solve for a missing value.

Simplified ratio

16 : 9

Decimal: 1.777778

What this does

Work with ratios two ways: simplify a ratio like 1920:1080 to its lowest terms, or solve a proportion where one of the four values is unknown (A is to B as C is to ?).

How to use it

1To simplify, enter both sides of the ratio and read the reduced form.
2To solve a proportion, fill any three of the four boxes and leave the unknown blank.
3Results, including the decimal equivalent, update as you type.

Examples

1920:1080 simplifies to 16:9
3:4 = 9:? solves to 12
2:5 as a decimal is 0.4

Frequently asked questions

How do you simplify a ratio?: Divide both numbers by their greatest common divisor. For 1920:1080 the GCD is 120, giving 16:9. The tool does this automatically.
Can it solve for a missing number in a proportion?: Yes. Enter three of the four values in the A:B = C:D form and leave one blank — the calculator cross-multiplies to find it.

More calculators

View all

Percentage CalculatorCalculate percentages, changes and shares.Age CalculatorCalculate exact age from a birth date.Discount CalculatorCalculate sale prices and savings.Date Difference CalculatorDays, weeks and months between dates.