Percentage Calculator
Work out percentages of a number, percentage change, increases, decreases, differences and reverse percentages.
Percentage of a number
30
15 ÷ 100 × 200
What percent is it?
15%
30 ÷ 200 × 100
Percentage change (increase or decrease)
+25% increase
(100 − 80) ÷ |80| × 100
Increase or decrease a number by a percentage
Increased: 275 Decreased: 225
250 × (1 ± 10 ÷ 100)
Percentage difference between two numbers
40%
|100 − 150| ÷ ((|100| + |150|) ÷ 2) × 100
Reverse percentage (find the original number)
Original: 100
105 ÷ (1 + 5 ÷ 100)
What this calculator does
Six everyday percentage questions in one place: a percentage of a number, what percent one number is of another, percentage change, adding or removing a percentage, the percentage difference between two numbers, and reverse percentages. Each answer updates as you type and shows the working.
Formulas
- Percentage of a number: percentage ÷ 100 × number. 15% of 200 is 30.
- What percent: part ÷ whole × 100. 30 is 15% of 200.
- Percentage change: (new − old) ÷ old × 100. From 80 to 100 is a 25% increase; from 100 to 80 is a 20% decrease.
- Increase or decrease: number × (1 + percentage ÷ 100) or number × (1 − percentage ÷ 100). 250 plus 10% is 275.
- Percentage difference: the gap between two numbers divided by their average. 100 and 150 differ by 40%.
- Reverse percentage: final value ÷ (1 + percentage ÷ 100). A price of 105 after a 5% increase started at 100.
Percentage change or percentage difference?
Use percentage change when one number came first, such as last month's sales and this month's. Use percentage difference to compare two numbers on an equal footing, such as two quotes for the same job. The difference is measured against the average, so the order does not matter.
Common mistakes
- Reversing a percentage with the same percentage: 100 plus 10% is 110, but 110 minus 10% is 99, not 100. Use the reverse percentage calculator instead.
- Removing 5% VAT by subtracting 5% from a VAT-inclusive price. Divide by 1.05 instead, or use the VAT calculator.
- Adding percentages from consecutive changes. A 10% rise followed by a 10% rise is a 21% rise in total.
Limitations
Answers are rounded to four decimal places for display. A percentage change from zero, or a reverse percentage after a 100% decrease, has no meaningful answer, so the calculator explains why instead of showing a number.
How do I work out a percentage increase between two numbers?
Subtract the old number from the new one, divide by the old number and multiply by 100. From 80 to 100: (100 − 80) ÷ 80 × 100 = 25%.
How do I find the original price before a percentage was added?
Divide the final price by 1 plus the percentage as a decimal. A price of 105 after a 5% increase was 105 ÷ 1.05 = 100.
Why is a 50% drop not undone by a 50% rise?
Each percentage is worked out from a different starting number. 100 minus 50% is 50, and 50 plus 50% is only 75. Getting back to 100 needs a 100% rise.
Can I use negative numbers?
Yes. Percentage change is measured against the size of the starting number, so going from −100 to −50 is shown as a 50% increase.
For prices, try the Discount Calculator, the Profit Margin Calculator or the UAE VAT Calculator.