Percentage Calculator

Calculate what a percentage is in absolute terms, what percentage one number is of another, or how large a percentage change is.

Result
170
20% of 850
Result
20%
170 of 850
Change
+20%
From 850 to 1020

How to use the percentage calculator

  1. Choose which type of percentage calculation you need with the buttons above the calculator.
  2. Enter your numbers — the calculator works out the answer automatically as you type.
  3. Read the explanation below to understand how the answer was calculated.

How percentages are calculated

Percent means "per hundred", and every percentage calculation builds on the same base formula:

Part ÷ Whole × 100 = Percent

To find what X% of Y is, rearrange the formula: take the percentage divided by 100, and multiply by the number. To find 20% of 850, you calculate 20 ÷ 100 × 850 = 170.

To find what percentage A is of B, use the base formula directly: 170 ÷ 850 × 100 = 20%.

To find a percentage change between two numbers, use the formula (new value − old value) ÷ old value × 100. If a number goes from 850 to 1020, the change is (1020 − 850) ÷ 850 × 100 = 20% increase.

Frequently asked questions

How do I calculate a percentage discount?

Use the "X % of Y" tab. Enter the discount percentage and the original price — the result shows how much you save. Subtract this from the original price to find the new price.

Can I calculate a negative percentage change?

Yes. Use the "% change" tab. If the number decreases, the calculator shows a negative percentage, meaning a decline.

What's the difference between percentage points and percent?

Percentage points are the direct difference between two percentage shares (e.g. from 20% to 25% is 5 percentage points), while percent change calculates how large the relative change is (5 ÷ 20 × 100 = 25% increase).