Percentage Calculator

What the Percentage Calculator does

The Percentage Calculator handles the handful of percentage calculations people actually need day to day: finding a percentage of a value, working out what percent one number is of another, and calculating percentage increase or decrease between two values.

How to use it

1. Choose the type of calculation you need from the dropdown.
2. Fill in the two values the selected calculation requires.
3. Click Calculate to see the result.

Common uses

• Working out a tip, tax, or commission as a percentage of a bill or sale.
• Checking what percentage a test score, survey response, or vote share represents.
• Calculating the percentage change between two figures, like a price increase or a sales dip.
• Verifying a discount or markup percentage applied to a price.
• Working through percentage-based homework or business math problems.

Good to know

Percentage increase and percentage decrease are calculated against the original (starting) value, not the new value — a 50% increase followed by a 50% decrease doesn't return you to the starting number, which trips people up more often than you'd expect. Picking the right calculation type in the dropdown matters more than the numbers themselves, since "20% of 150" and "20 is what percent of 150" are different questions with different formulas.

Percentage confusion is one of the more common sources of everyday math mistakes, particularly around percentage change — people often average two percentages when they should be compounding them, or apply a percentage decrease to the wrong base value. Selecting the correct calculation type for the specific question you're actually asking is usually the harder part of getting percentage problems right; the arithmetic itself is simple once the right formula is applied.