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Math

Percentage Calculator

Find a percentage of a number, what percent one number is of another, and the percentage change between two values.

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What is X% of Y?

X is what percent of Y?

Percentage change from X to Y

How to use the percentage calculator

The calculator has three parts. Fill in the two boxes of the question you want answered and press Calculate. You can type numbers with or without thousands separators, for example 1,250 or 1250.

  • What is X% of Y? Finds a part of a whole, such as 15% of 200.
  • X is what percent of Y? Tells you how large one number is compared with another.
  • Percentage change from X to Y Shows how much a value went up or down, in percent.

Formulas

Percent of a number

Part = Percent / 100 × Whole. For example, 15% of 200 is 0.15 × 200 = 30.

What percent one number is of another

Percent = Part / Whole × 100. For example, 30 out of 120 is 30 / 120 × 100 = 25%.

Percentage change

Change = (New − Old) / |Old| × 100. A positive result is an increase and a negative result is a decrease. Going from 80 to 100 is a 25% increase, while going from 100 to 80 is a 20% decrease.

Good to know

  • A percentage change cannot be calculated when the starting value is zero, because there is nothing to compare against.
  • Percentage change is not symmetric: a 50% drop followed by a 50% rise does not bring you back to where you started.
  • Percentage points are not the same as percent. An interest rate moving from 4% to 5% rises by one percentage point, which is a 25% increase.

Frequently asked questions

How do I calculate a percentage of a number?

Divide the percentage by 100 and multiply it by the number. For example, 20% of 85 is 0.20 × 85 = 17.

How do I work out a percentage increase?

Subtract the old value from the new value, divide the result by the old value and multiply by 100. From 50 to 65 is (65 − 50) / 50 × 100 = 30%.

Why can't I calculate a percentage change from zero?

The formula divides by the starting value. Dividing by zero is undefined, so any change from zero cannot be expressed as a percentage.

What is the difference between percent and percentage points?

Percentage points measure the simple difference between two percentages, while percent measures the relative change. Going from 10% to 12% is a rise of 2 percentage points, or 20%.