Percentage Calculator Online
Five calculators on a single page for every everyday percentage question: sales, a pay raise, sales tax, a grade, how a figure has changed. The result appears instantly, with the formula so you understand the calculation.
- 5 calculators
- Instant result
- Detailed formula
- Free
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How to calculate a percentage?
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Choose your question
X% of Y, what percentage X represents, the change between two values, price after a discount or increase, or the starting value.
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Enter the values
Type your numbers: the result updates with every digit, no button to click.
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Read the formula
Below each result, the calculation is broken down step by step so you can check it or redo it by hand.
Every percentage calculation in one place
Percentage of a number
What's 15% of 240? The answer appears as you type.
Rate of change
Increase or decrease in percentage between a starting value and an ending value.
Discount and increase
Sale price, raised salary, total with tax: apply a percentage increase or decrease.
Initial value
Find the price before a discount or the amount before an increase, from the final price.
Calculate X% of a number and a proportion
To calculate a percentage of a number, multiply the number by the percentage then divide by 100: 20% of 80 = 80 × 20 / 100 = 16. The other way around, to find out what percentage a value represents of a total, divide the part by the total then multiply by 100: 15 out of 60 = 15 / 60 × 100 = 25%. That's the calculation for turning a grade into a percentage, a share of a budget, or a success rate.
Price after a discount, an increase, and the value before a reduction
To apply a discount, multiply the price by (1 − rate): an item at $50 with a 30% discount costs 50 × 0.70 = $35. For an increase, multiply by (1 + rate): a pre-tax price of $100 with 20% sales tax gives $120 with tax included. To find the original value, divide: an item paid for at $64 after a 20% discount originally cost 64 / 0.80 = $80, and $120 with tax included corresponds to 120 / 1.20 = $100 before tax. Note that a 10% increase followed by a 10% decrease doesn't bring you back to the starting point: 100 becomes 110, then 99.
Calculate a rate of change as a percentage
The rate of change is calculated as: (ending value − starting value) / starting value × 100. Going from 40 to 50 is an increase of (50 − 40) / 40 × 100 = +25%; going from 50 to 40 is a decrease of −20%. This is used to track how a price, a rent, a salary, revenue, or a population has changed. The calculator automatically shows whether it's an increase or a decrease, and breaks down the formula used.
Frequently Asked Questions
How do I calculate 20% of a number?
Multiply the number by 20 then divide by 100, or multiply it directly by 0.20. For example, 20% of 80 = 16.
How do I calculate a price after a discount?
Multiply the price by (1 − discount). An item at $50 with a 30% discount costs 50 × 0.70 = $35. The “Increase or decrease by X%” calculator does this for you.
How do I calculate a percentage increase between two values?
Compute (ending value − starting value) / starting value × 100. Going from 40 to 50, the increase is 25%.
How do I find the price before a discount?
Divide the price paid by (1 − discount). An item paid for at $64 after a 20% discount originally cost 64 / 0.80 = $80. Don't just add 20% to the price paid: 64 + 20% would give $76.80, which is wrong.
Why doesn't a 10% decrease cancel out a 10% increase?
Because the decrease applies to a value that's already been increased. 100 + 10% = 110, then 110 − 10% = 99. To get back to 100, you'd need a decrease of about 9.09%.