Percentage Calculator
Three modes in one. Find any percentage, ratio, or change in seconds.
%
X% of Y
—
How the Percentage Calculator Works
This calculator covers the three most common percentage calculations in one tool. Switch between modes using the tabs at the top.
- X% of Y — Find a percentage of a number (e.g. 15% of 200 = 30).
- What % — Find what percentage X is of Y (e.g. 30 is 15% of 200).
- % Change — Find the percentage increase or decrease between two values.
Frequently Asked Questions
What is the formula for percentage?
To find X% of Y, multiply Y by X and divide by 100. For example, 20% of 150 = 150 × 20 / 100 = 30. To find what percentage X is of Y, divide X by Y and multiply by 100. For example, 30 ÷ 150 × 100 = 20%.
How do I calculate percentage change?
Percentage change = ((New Value − Old Value) / |Old Value|) × 100. A positive result means an increase; a negative result means a decrease. For example, going from 80 to 100 is a 25% increase. Going from 100 to 80 is a 20% decrease.
Why is a 50% increase followed by a 50% decrease not back to the original?
Because percentages are relative to the current value, not the original. If you start at 100 and increase by 50%, you get 150. Then a 50% decrease of 150 gives you 75 — not 100. This is why percentage changes are not simply reversible and why the order of operations matters.
You might also need
Complementary tools based on what you're doing