Percentage Calculator
The four percentage questions people ask most, answered as you type, with the working shown.
Percentage of a number
What percent is it?
Percentage change
Add or remove a percentage
How your percentage is worked out
Per cent means “out of 100”, so every sum starts by dividing or multiplying by 100.
- 1
Percent to decimal
20 ÷ 100 = 0.2
- 2
Multiply
0.2 × 150 = 30
- 3
Check it backwards
30 ÷ 150 × 100 = 20%
- 4
The answer
20% of 150 = 30
Read more: all four percentage formulas and a common trap
"Per cent" means "out of 100", so 20% is 20 out of every 100, or 0.2. Every percentage question is one of these four:
| Question | Formula | Example |
|---|---|---|
| What is X% of Y? | X ÷ 100 × Y | 20% of 150 = 30 |
| X is what % of Y? | X ÷ Y × 100 | 30 is 20% of 150 |
| % change from X to Y | (Y − X) ÷ X × 100 | 80 → 100 is +25% |
| Y plus X% | Y × (1 + X ÷ 100) | 200 + 15% = 230 |
Worked example
A jacket went from 80 to 100. The change is (100 − 80) ÷ 80 × 100 = +25%. And 20% of 150 is 20 ÷ 100 × 150 = 30, so 30 is 20% of 150.
A common trap
A rise and a fall of the same percentage do not cancel out. If a price goes up 25% from 80 to 100, a 25% drop takes it to 75, not back to 80. To undo a 25% rise you need a 20% fall. The percentage change is always measured from the starting value.
Taking a percentage off
To work out a discount or remove tax, enter a negative percentage in the last box. For example, 200 plus −15% gives 170.