Percentage Calculator

How to use

1. Calculator 1: find what a percent of a number is (e.g. 20% of 150 = 30).
2. Calculator 2: find what percent one number is of another (e.g. 30 is 60% of 50).
3. Calculator 3: find the percentage change between two values - positive means increase, negative means decrease.

Use cases

1. Use case: Calculate discounts Work out what 20% off $150 is, or what percent you saved compared with the original price.

2. Use case: Analyze scores and metrics Find what percent a score is of the total, or the percentage increase between two revenue periods.

Practical tips

The three percentage questions are different computations: what is X percent of Y, X is what percent of Y, and the percent change between two values — pick the right input mode before typing. Percent change and percentage points are not the same: an increase from 10 to 15 percent is a 50 percent change but a 5 point rise. For discounts, apply the percent to the original price, not to a running total of markdowns. Like every tool on this site, the Percentage Calculator runs entirely in your browser: the data you enter never leaves your device, nothing is uploaded to a server, and the tool keeps working if your connection drops.

Common mistakes

Percentage errors are famous because the arithmetic is easy but the framing is not:

• Confusing percent change with percentage points: a rise from 10 to 15 percent is a 50 percent change but a 5 point rise.
• Applying a discount to a running total of markdowns instead of to the original price.
• Adding percentages of different bases — 30 percent of A plus 20 percent of B is not 50 percent of anything.
• Picking the wrong input mode: 'what is X percent of Y', 'X is what percent of Y' and percent change are three different computations.

Frequently asked questions