Percentage Calculator
Every common percentage question in one place – percent of a number, percentage change, increase or decrease, reverse percentages, marks and more – with the working shown.
- 9 calculators
- Step-by-step working
- Updates as you type
- Runs in your browser
What is X% of Y?
X is what percent of Y?
X is Y% of what?
Percentage change (increase or decrease)
Increase or decrease a number by a percent
Percentage difference between two numbers
Value before a percentage change (reverse %)
Marks percentage
Percent ⇄ decimal ⇄ fraction
Calculated in your browser. Nothing is saved.
How to use the percentage calculator
- Find the right calculatorPick the question you’re trying to answer – each box is written as a sentence, like “What is 15% of 200?”. Use the chips at the top to jump to one.
- Type your numbersThe answer updates as you type. You can paste numbers with commas or currency symbols.
- Check the workingEach result shows the formula with your numbers, so you can follow it or copy it for homework or reports.
Percentage formulas at a glance
| Question | Formula | Example |
|---|---|---|
| What is P% of N? | P ÷ 100 × N | 15% of 200 = 30 |
| A is what % of B? | A ÷ B × 100 | 45 of 60 = 75% |
| A is P% of what? | A ÷ (P ÷ 100) | 30 is 15% of 200 |
| % change from A to B | (B − A) ÷ A × 100 | 80 → 100 = +25% |
| Increase N by P% | N × (1 + P ÷ 100) | 500 + 12% = 560 |
| % difference | |A − B| ÷ ((A + B) ÷ 2) × 100 | 80 vs 100 = 22.2% |
| Before a P% increase | Final ÷ (1 + P ÷ 100) | 1180 ÷ 1.18 = 1000 |
Mental maths shortcuts
- 10% – move the decimal point one place left: 10% of 350 = 35.
- 5% – half of 10%: 5% of 350 = 17.5.
- Swap trick – P% of N equals N% of P, so 8% of 50 = 50% of 8 = 4.
- 25%, 50%, 75% – a quarter, a half and three quarters.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. For example, 15% of 200 = 15 ÷ 100 × 200 = 30. A quick trick: 10% is the number divided by 10, so 15% is 10% plus half of that again.
How do I work out what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 45 out of 60 is 45 ÷ 60 × 100 = 75%.
How do I calculate percentage increase or decrease?
Subtract the old value from the new value, divide by the old value and multiply by 100. From 80 to 100 is (100 − 80) ÷ 80 × 100 = 25% increase. From 100 to 80 is a 20% decrease – the starting value matters.
What’s the difference between percentage change and percentage difference?
Percentage change compares a new value with an old one, so direction matters. Percentage difference compares two values with no “before” and “after”, so it divides by their average – 80 and 100 differ by 22.2% either way round.
How do I find the original price before a discount or tax?
Divide the final price by (1 + rate) for an increase or (1 − rate) for a decrease. A price of ₹1,180 including 18% GST was ₹1,180 ÷ 1.18 = ₹1,000 before tax. Use the “Value before a percentage change” calculator.
Why doesn’t a 20% increase followed by a 20% decrease get back to the start?
Because the second percentage is taken from a bigger number. 100 + 20% = 120, then 120 − 20% = 96. To undo a 20% increase you need a 16.67% decrease.
How do I calculate my marks percentage?
Add up the marks you got, divide by the total maximum marks and multiply by 100. 425 out of 500 is 85%. The Marks calculator does this for any number of subjects with different maximums.
What is a percentage point?
It’s the simple difference between two percentages. An interest rate rising from 6% to 8% is up 2 percentage points – but that’s a 33.3% increase in the rate itself.
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