Ratio Calculator

Simplify a ratio, split a total, or solve a proportion. Not a financial ratio.

Mode *

First part *

Second part *

Smart Tips

• A ratio a:b compares two quantities in the same unit. It is not a debt-to-income ratio or a price-to-earnings ratio.

• Simplifying divides both parts by their greatest common divisor. 8:12 becomes 2:3.

• Sharing a total uses each part divided by the sum of the parts. 2:3 of 100 is 40 and 60.

• A proportion is a/b = c/d. The page solves for the one value you mark as missing.

The Formula

a / b = c / d

a:b = Ratio
Two parts, then divide by the gcd

T = Total
Split by each part over the sum

a/b = Proportion
Equal to c/d, with b and d not zero

ad = Cross product
Equals bc when the proportion is true

Decimals are scaled to whole numbers before the greatest common divisor is used. Share parts must be greater than zero. A proportion with a zero denominator is rejected.

Key Insights

Not a financial ratio

This page does not compute margin, debt-to-income, or any market ratio. The inputs are plain numbers.

Three jobs

Simplify a:b, split a total in the ratio a:b, or solve one missing term in a/b = c/d.

Zero denominators

OpenStax defines a proportion with both denominators nonzero. The page refuses a denominator of zero instead of dividing by it.

Shares add up

The two shares are total × part / (part + part). For positive parts they add back to the total.

Frequently Asked Questions

Simplify turns a:b into lowest terms. Share splits a total in the ratio of two positive parts. Proportion solves a/b = c/d for the one missing value.

No. It does not compute a leverage ratio, a liquidity ratio, or debt-to-income. Those need different inputs. This page only compares and splits plain numbers.

Decimals are scaled to integers, then both parts are divided by their greatest common divisor. 8:12 becomes 2:3. 0:5 becomes 0:1. 0:0 is rejected because there is nothing to compare.

Each share is the total times that part, divided by the sum of the parts. A 2:3 share of 100 is 40 and 60. Both parts must be greater than zero.

A proportion says a/b = c/d, so a×d = b×c. The missing value is the one that makes the cross products equal. If a known or resulting denominator would be zero, the page stops.

A ratio compares two quantities, as in OpenStax Prealgebra 2e, section 5.6. A proportion is an equation a/b = c/d with b and d not zero, from section 6.5 of the same book. Shares split a total in proportion to the parts. No outside data feed is used.

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Result

Enter values to calculate

First part

Second part

Note:This page compares and splits plain numbers. It does not compute a financial ratio. A proportion with a denominator of zero is rejected.