Percentages
From discounts to growth, understand what a percentage really tells you.
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Discount Calculator
Work out the sale price and savings from a percentage discount.
Percentage Calculator
Find what percentage a part represents of a whole.
Percentage Change Calculator
Compare an original value and a new value to find relative change.
Percentage Decrease Calculator
Apply a percentage decrease to an original value.
Percentage Increase Calculator
Apply a percentage increase and find the new value.
Percentage Error Calculator
Compare a measured value with a nonzero reference using absolute percentage error.
Percentage of a Number
Find a percentage of any nonnegative number.
Reverse Percentage Calculator
Recover an original value after a known percentage increase.
Successive Discounts Calculator
Apply two consecutive percentage discounts and find the effective discount.
Questions and worked answers
Are two 20% discounts equal to 40%?
Two discounts apply to different bases. Start with a price of 100. A 20% discount leaves 80; a second 20% discount removes 16 and leaves 64. The total redu
How do you calculate a discount?
Multiply the original price by the discount percentage divided by 100, then subtract that saving from the price.
How do you calculate percentage decrease?
Subtract the new value from the original, divide by the original, and multiply by 100.
How do you calculate percentage increase?
Subtract the original value from the new value, divide by the original value, and multiply by 100.
How do you calculate a percentage?
Divide the part by the whole and multiply by 100. For example, 20 out of 80 is 25%.
What is the difference between percent and percentage points?
Percentage points measure the difference between two percentages. Percent change measures that difference relative to the starting percentage.
What was the original price before a 20% increase?
If a price after a 20% increase is 120, the original price was 100: divide 120 by 1.20. Subtracting 20% of 120 produces 96 because it uses the new price as
What is 20% of 80?
20% of 80 is 16. Write 20% as 0.20, then multiply 0.20 by 80.
Guides and examples
Combining discounts correctly
Two discounts apply to different bases. Start with a price of 100. A 20% discount leaves 80; a second 20% discount removes 16 and leaves 64. The total redu
Understanding Percentage Change
Percentage change compares a difference with its original value. The starting value is the reference point.
How Percentages Work
A percentage describes a quantity per hundred. It lets you compare shares even when the underlying totals differ.
Finding an original value after a percentage change
If a price after a 20% increase is 120, the original price was 100: divide 120 by 1.20. Subtracting 20% of 120 produces 96 because it uses the new price as
Key concepts
Percentage
A percentage is a ratio expressed as a number of parts per hundred.
Successive discounts versus an added discount
Two discounts apply to different bases. Start with a price of 100. A 20% discount leaves 80; a second 20% discount removes 16 and leaves 64. The total redu
Percentage increase versus reversing an increase
If a price after a 20% increase is 120, the original price was 100: divide 120 by 1.20. Subtracting 20% of 120 produces 96 because it uses the new price as
