Percentages come up constantly — tips, discounts, grades, growth rates — but the three common percentage questions each need a different formula. This calculator covers all three: finding a percentage of a number, finding what percent one number is of another, and finding the percent change between two numbers, all updating live as you type.
How to use the percentage calculator tool
- 1
Pick a calculation
Choose X% of Y, X is what % of Y, or percent change.
- 2
Enter your numbers
Type in the two values — the result updates instantly.
- 3
Read the result
The answer is shown immediately, no calculate button needed.
Common use cases
Calculate a tip or tax
Find what a percentage of a bill or price actually comes out to.
Check a test score
Find what percent 42 out of 50 actually is.
Track a price or metric change
Find the percent increase or decrease between two values, like last month's revenue vs. this month's.
Frequently asked questions
Use the "% change" mode: enter the original (from) value and the new (to) value. A positive result is a percent increase, a negative result is a decrease.