Percentage Calculator
Three everyday percentage questions in one place. Each calculator shows its working, so you can check the method as well as the answer.
What is X% of Y?
X is what percent of Y?
X is Y% of what?
How percentages work
“Per cent” means “per hundred”, so 20% is simply 20 ÷ 100 = 0.2. Every percentage problem links three quantities — the part, the whole and the percentage — and if you know any two you can find the third.
part = (percentage ÷ 100) × whole
percentage = (part ÷ whole) × 100
whole = part ÷ (percentage ÷ 100)
Worked examples
What is 20% of 50?
- Convert 20% to a decimal: 20 ÷ 100 = 0.2
- Multiply by the whole: 0.2 × 50 = 10
Answer: 20% of 50 is 10.
15 is what percent of 60?
- Divide the part by the whole: 15 ÷ 60 = 0.25
- Multiply by 100: 0.25 × 100 = 25
Answer: 15 is 25% of 60.
30 is 25% of what number?
- Convert 25% to a decimal: 0.25
- Divide the part by it: 30 ÷ 0.25 = 120
Answer: 30 is 25% of 120.
Where you will use this
- Working out a test score as a percentage (e.g. 42 out of 50 is 84%).
- Finding a tip, service charge or tax amount on a bill.
- Checking what share of a budget or a group a figure represents.
- Reading survey results and statistics correctly.
Mental shortcuts
10% of any number is that number with the decimal point moved one place left (10% of 84 is 8.4). From there, 5% is half of 10%, 20% is double it, and 1% is a tenth of it. Percentages are also reversible: 8% of 50 is the same as 50% of 8, which is 4.
Common questions
Can a percentage be more than 100%?
Yes. 150% of 40 is 60 — one and a half times the number. Percentages over 100 are common when describing growth or comparing a larger value with a smaller one.
How do I enter a negative percentage?
Type a minus sign before the number, for example −10. A negative percentage of a positive number gives a negative result.