Percentage Calculator
This percentage calculator solves the three most common percentage problems: what X% of a number is, what percentage one number is of another, and the percentage increase or decrease from one value to another.
About this tool
This percentage calculator solves the three most common percentage problems: what X% of a number is, what percentage one number is of another, and the percentage increase or decrease from one value to another.
How to use it
- Pick the question you need: X% of Y, X as a % of Y, or % change from X to Y.
- Type the two numbers into that row.
- Read the result instantly — increases show in green, decreases in red.
Good to know
- X% of Y = X ÷ 100 × Y. Example: 15% of 80 is 12.
- X as a percentage of Y = X ÷ Y × 100. Example: 12 is 15% of 80.
- Percentage change = (new − old) ÷ |old| × 100. Example: from 80 to 100 is +25%.
- A percentage change cannot be calculated from a starting value of zero.
Runs entirely in your browser — nothing you enter is uploaded or stored.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. For example, 15% of 80 is 0.15 × 80 = 12.
How do I work out percentage increase?
Subtract the old value from the new value, divide by the old value and multiply by 100. Going from 80 to 100 is a 25% increase.
Why is a 50% drop not undone by a 50% rise?
Percentages apply to different starting values. 100 falling 50% becomes 50, and a 50% rise on 50 only gets back to 75.
What is the difference between percent and percentage points?
Percentage points measure the gap between two percentages. A rate rising from 4% to 5% is up 1 percentage point, which is a 25% increase.