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Percentage Calculator

Work out a percentage of a number, find what percent one value is of another, or measure the percentage change between two values. All three calculators update as you type.

What is X% of Y?

Result–

X is what percent of Y?

Result–

Percentage change from X to Y

Change–

Results are calculated in your browser from the numbers you enter. Nothing is uploaded or stored.

How to use the Percentage Calculator

  1. Pick the calculator that matches your question: percent of a number, what percent, or percentage change.
  2. Type your two numbers into the boxes.
  3. Read the result straight away; it updates as you edit.

Formulas used

Worked examples

15% of 240 is 15 ÷ 100 × 240 = 36. 45 is 45 ÷ 180 × 100 = 25% of 180. A price that moves from 80 to 100 changes by (100 − 80) ÷ 80 × 100 = +25%.

When percentages trip people up

A rise of 50% followed by a fall of 50% does not return you to the start: 100 becomes 150, then 75. Percentage change is always measured against the starting value, so reversing it needs a different percentage. Percentage points are also different from percent: moving from 10% to 12% is a rise of 2 percentage points but a 20% relative increase.

Frequently asked questions

How do I calculate a percentage of a number?

Divide the percentage by 100 and multiply by the number. For example, 20% of 150 is 0.20 × 150 = 30.

How do I find what percent one number is of another?

Divide the first number by the second and multiply by 100. For example, 30 out of 120 is 30 ÷ 120 × 100 = 25%.

How is percentage increase calculated?

Subtract the old value from the new value, divide by the old value and multiply by 100. A negative answer means a decrease.

Why is percentage change not available when the starting value is 0?

Change is measured against the starting value, and dividing by zero is undefined, so the calculator shows a dash instead of a number.

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Last updated: November 6, 2026