Percentage Calculator
Three modes: find a percentage, what percentage, and percentage change.
What is the Percentage Calculator?
A percentage calculator handles the everyday percent maths that is easy to fumble in your head — finding 15% of a bill, working out what percentage you scored on a test, or seeing how much a price rose or fell. It covers the three common cases in one place, so you pick the one you need and read off the answer. Students, shoppers and anyone dealing with marks, discounts or changes in figures will find it faster and safer than doing it by hand.
How to use the Percentage Calculator
- Choose the type of calculation you need.
- Enter your numbers — for example the amount and the percentage.
- Read the result straight away.
Why use Quably's Percentage Calculator?
- Three calculation modes in one tool
- Instant, accurate answers
- No formulas to remember
- Works on any device
- Free with no sign-up
Percentage Calculator formula
Percentage of a number: Result = (Percentage ÷ 100) × Number. Percentage change: Change % = ((New − Old) ÷ Old) × 100.
Examples
A percentage of a number
20% of 250 is (20 ÷ 100) × 250 = 50.
Percentage change
A price going from 80 to 100 is ((100 − 80) ÷ 80) × 100 = a 25% increase.
Frequently asked questions
How do I find a percentage of a number?
Divide the percentage by 100 and multiply by the number. For example, 10% of 40 is 0.10 × 40 = 4.
How do I calculate percentage change?
Subtract the old value from the new value, divide by the old value, then multiply by 100.
How do I work out what percentage one number is of another?
Divide the part by the whole and multiply by 100 — for example 25 out of 50 is (25 ÷ 50) × 100 = 50%.
Is the percentage calculator free?
Yes, it is free and needs no account.