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Daily Dose of Utilities

Percentage Calculator

To find a percentage of a number, divide the percent by 100 and multiply by the number: 15% of 200 is 0.15 × 200 = 30.

%

15% of 200

30

Show the math

  1. 1

    Turn the percent into a decimal

    15 ÷ 100 = 0.15

    “Percent” means “per hundred”, so divide by 100.

    = 0.15

Read the steps as text
  1. Turn the percent into a decimal. 15 ÷ 100 = 0.15 “Percent” means “per hundred”, so divide by 100.
  2. Multiply by the whole. 0.15 × 200 = 30 The decimal is the fraction of the whole you want.

How percentages work

A percentage is a fraction out of 100. Saying 15% means 15 per hundred, or 0.15 as a decimal. Almost every percentage problem is a rearrangement of the same relationship: part = percent × whole.

This calculator covers the three questions people ask most: what is X% of Y, X is what percent of Y, and what is the percentage change from X to Y. Press Play under the result to watch each step happen, or read the same steps as text.

The three formulas

X% of Y = (X ÷ 100) × Y. Example: 20% of 80 = 0.20 × 80 = 16.

X is what % of Y = (X ÷ Y) × 100. Example: 16 is 20% of 80 because 16 ÷ 80 × 100 = 20.

Percentage change = ((new − original) ÷ original) × 100. Example: from 80 to 100 is (20 ÷ 80) × 100 = 25% increase.

Frequently asked questions

How do I calculate a percentage of a number?
Divide the percentage by 100 to get a decimal, then multiply by the number. For 25% of 60: 25 ÷ 100 = 0.25, and 0.25 × 60 = 15.
How do I calculate percentage increase?
Subtract the original from the new value, divide by the original, and multiply by 100. Going from 50 to 65 is (15 ÷ 50) × 100 = 30%.
Why is a 50% increase followed by a 50% decrease not back to the start?
Because the second percentage is taken from the larger number. 100 up 50% is 150, and 150 down 50% is 75, not 100.

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