Free tool
Every percentage question, answered as you type
Five calculators on one page: a percent of a number, what percent one number is of another, the change between two numbers, adding or removing a percentage, and finding the original amount.
What you get
- Shows the working for every answer
- Percentage change and reverse percentages
- Works with decimals and negatives
Pricing a product? Try the profit margin calculator.
What is% of?30
15 ÷ 100 × 200 = 30
is what % of?25%
30 ÷ 120 × 100 = 25%
% change fromto?25%
(100 − 80) ÷ 80 × 100 = 25% (increase)
increased by% =295
250 × (1 + 18 ÷ 100) = 295. Use a minus sign to decrease.
is% of what?150
45 ÷ (30 ÷ 100) = 150
Answers update as you type. Nothing is sent anywhere.
Percentages, briefly
Most percentage mistakes come from dividing by the wrong number.
A rise from 80 to 100 is 25%, but a fall from 100 to 80 is 20%. The change is always divided by where you started. The calculator does it the right way round and shows the sum.
- How do I work out a percentage of a number?
- Divide the percentage by 100 and multiply by the number. 15% of 200 is 15 ÷ 100 × 200 = 30.
- How do I calculate percentage change?
- Take the new value minus the old value, divide by the old value, and multiply by 100. From 80 to 100: (100 − 80) ÷ 80 × 100 = 25% increase.
- How do I add a percentage to a price, like tax?
- Multiply by 1 plus the percentage as a decimal. 250 plus 18% is 250 × 1.18 = 295. To take a percentage off, use a minus sign: 250 − 18% is 250 × 0.82 = 205.
- How do I find the original price before a percentage was added?
- Divide by 1 plus the percentage. If 295 includes 18% tax, the price before tax is 295 ÷ 1.18 = 250. The last calculator does the related sum: if 45 is 30% of a number, the number is 45 ÷ 0.30 = 150.
- Working out tax on invoices?
- The GST / VAT calculator adds or removes tax at any rate and shows a printable breakdown.
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