Percentages without the headache
Percentages turn up everywhere: marks, discounts, tax, interest, growth. This page answers the four questions people ask most, written as sentences you complete: What is 15% of 2,400?, 45 is what percent of 180?, 90 is 30% of what number? and What's the percentage change from 1,200 to 1,500?
Results update as you type, and each has a copy button. The formulas are listed underneath so you can check the working.
How to calculate a percentage
- 1
Find the right sentence
Pick the question that matches yours.
- 2
Fill in the blanks
Type your numbers into the boxes.
- 3
Copy the answer
Results appear instantly.
Key features
Four calculators
Percent of, percent is, reverse percentage and change.
Plain-English layout
No formulas to remember.
Instant results
With copy buttons.
Decimals and negatives
Handled correctly.
Common uses
- Exam marks: Convert marks to a percentage.
- Shopping: Work out discounts and tax.
- Work: Growth rates, targets and shares.
Quick examples
| Question | Answer |
|---|---|
| What is 18% of 2,500? | 450 |
| 432 out of 500 as a percentage | 86.4% |
| 300 is 20% of what? | 1,500 |
| Change from 80 to 100 | 25% increase |
Tips and good to know
- Percentage change is calculated on the original value, so going from 100 to 150 is +50% but 150 to 100 is −33.3%.
- For repeated increases or decreases, try the Percentage Increase Calculator.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. 15% of 2,400 = 2,400 × 15 ÷ 100 = 360.
How do I work out my exam percentage?
Use the second calculator: marks obtained is what percent of total marks. 432 out of 500 = 86.4%.
How do I find the original number from a percentage?
Use the third calculator. If 90 is 30% of a number, the number is 90 × 100 ÷ 30 = 300.