Percentage Calculator
Find X% of a number, what percent one number is of another, and percentage increase or decrease.
What is X% of Y?
X is what percent of Y?
Percentage increase or decrease
Runs in your browser — your data never leaves your device.
About the Percentage Calculator
Percentages appear everywhere — exam marks, shop discounts, salary increments, interest rates and price changes. This percentage calculator answers the three questions people ask most often, each in its own box so you never have to rearrange a formula yourself.
Every result shows the exact working, so you can copy the steps into homework or double-check a bill.
How to use the Percentage Calculator
- Pick the box that matches your question.
- Enter the two numbers. Decimals and negative numbers are allowed.
- Press Calculate. The answer and the working appear under the box.
- Change any number and the answer updates automatically.
Formula
- X% of Y: (X ÷ 100) × Y
- X is what percent of Y: (X ÷ Y) × 100
- Percentage change from A to B: ((B − A) ÷ |A|) × 100
A positive change is an increase; a negative change is a decrease.
Examples
- 15% of 2,400 = 0.15 × 2,400 = 360
- 45 out of 60 marks = 45 ÷ 60 × 100 = 75%
- Price rises from 80 to 100 = (100 − 80) ÷ 80 × 100 = 25% increase
- Weight drops from 90 kg to 81 kg = (81 − 90) ÷ 90 × 100 = 10% decrease
Frequently asked questions
How do I calculate the percentage of marks?
Divide the marks you got by the total marks and multiply by 100. For example, 420 out of 500 is 420 ÷ 500 × 100 = 84%. Use the second box: "X is what percent of Y".
Is a 50% increase followed by a 50% decrease the same as no change?
No. If 100 rises 50% it becomes 150; a 50% decrease from 150 gives 75. Each percentage is taken from a different starting value.
Why can't I calculate a percentage change from zero?
Percentage change divides by the starting value. Dividing by zero is undefined, so any change from 0 cannot be expressed as a percentage.
What is the difference between percentage and percentage points?
If an interest rate goes from 10% to 12%, it rose by 2 percentage points, but by 20% in relative terms (2 ÷ 10 × 100).