Percent Proportion

A percent proportion is the proportion part/whole = percent/100. It is the fastest way to solve percent problems: find the part, find the percent, or find the whole — fill in any two values and the calculator finds the third, with the proportion, the cross-multiplication and the answer shown.

Percent Proportion Calculator

part / whole = percent / 100 — fill in any two values.

Part

Whole

Percent (%)

Example: 25% of 200 is 50. Leave the value you want to find blank.

What Is a Percent Proportion?

A percent proportion is part/whole = percent/100. It turns any percent question into a proportion you already know how to solve. The word “percent” means “per hundred”, so 25% is the ratio 25/100. Once you set up part/whole = percent/100, cross-multiply and divide, just like any other proportion.

Three Kinds of Percent Problems

Find the part: What is 25% of 200? Set x/200 = 25/100, cross-multiply: 100x = 5,000, x = 50. Find the percent: What percent of 200 is 50? Set 50/200 = x/100, cross-multiply: 200x = 5,000, x = 25%. Find the whole: 50 is 25% of what number? Set 50/x = 25/100, cross-multiply: 25x = 5,000, x = 200. The calculator above solves all three — just leave the unknown blank.

Percent Increase, Decrease and Discounts

Percent proportions also solve discounts and tax. A $80 jacket at 20% off: the discount is 20% of 80, which is $16, so you pay $64. A price that rises from $50 to $60 has increased by $10, which is 10/50 = 20%. Always be clear about what the “whole” is — the discount is a percent of the original price, not of the sale price.

Worked Examples

Example 1: 30 students, 40% are girls. How many girls? x/30 = 40/100, 100x = 1,200, x = 12 girls. Example 2: You scored 45 out of 60. What percent is that? 45/60 = x/100, 60x = 4,500, x = 75%. Example 3: 18 is 15% of what number? 18/x = 15/100, 15x = 1,800, x = 120.

Percent Proportion FAQs

What is the percent proportion formula?

part ÷ whole = percent ÷ 100. Fill in any two values and cross-multiply to find the third.

How do you find the percent of a number?

Multiply the number by the percent and divide by 100. For 25% of 200: 25 × 200 ÷ 100 = 50.

What is the difference between a percent proportion and a percent equation?

They are the same idea in two forms. The percent proportion is part/whole = percent/100; the percent equation is part = percent × whole. Both give the same answer.