How to Calculate a Percentage (5 Different Ways)
Published September 19, 2026 · 2 min read
"Percentage" questions actually come in several different flavors — what's 20% of 150, what percent is 30 of 150, or what's the percent change from 100 to 130 — and each needs a different formula. This tool covers all the common cases in one place.
Try Percentage CalculatorSteps
- 1
Open the Percentage Calculator tool
Go to the percentage calculator.
- 2
Choose the calculation type
Pick from: A% of B, A is what % of B, % change from A to B, B increased by A%, or B decreased by A%.
- 3
Enter your numbers
Fill in A and B for your chosen calculation.
- 4
Read the result
The answer is calculated instantly.
Frequently asked questions
"% change from A to B" tells you the percentage difference between two known values; "B increased by A%" instead calculates a new value after applying a percentage increase to B.
Yes — "B decreased by A%" handles that calculation directly, alongside the increase version.
Yes — all five calculation modes work correctly with negative values where the math is meaningful.
Because every common percentage question is covered in one tool, there's no need to remember which formula applies to which kind of question.