Percentage of a number
What is % of ?
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Percentage Calculator
Work out a percentage of a number, what percent one number is of another, a percentage increase or decrease, or the difference between two numbers. Each answer shows the formula with your numbers in it.
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What percent is it?
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Percentage increase or decrease
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Percentage difference
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Add or take off a percentage
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The formulas
- X% of Y = X ÷ 100 × Y. 20% of 150 is 30.
- X is what percent of Y = X ÷ Y × 100. 30 is 20% of 150.
- X is P% of what = X ÷ (P ÷ 100). 30 is 20% of 150.
- Percentage change from X to Y = (Y − X) ÷ |X| × 100. From 80 to 100 is an increase of 25%; from 100 to 80 is a decrease of 20%.
- Percentage difference = |X − Y| ÷ ((|X| + |Y|) ÷ 2) × 100. Between 80 and 100 it is about 22.22%.
- Increase X by P% = X × (1 + P ÷ 100); decrease = X × (1 − P ÷ 100). 80 increased by 15% is 92.
You can type negative numbers, and numbers with commas between groups of three digits, such as 1,250.5. A comma anywhere else, such as in 12,34, is refused rather than guessed. Answers are shown to at most 10 decimal places.
Percentage change or percentage difference?
Use percentage change when one number came first: a price that went from $80 to $100 rose by 25%. The order matters: going back from $100 to $80 is a fall of 20%, not 25%, because the change is measured against the starting value.
Use percentage difference when neither number came first, such as two shops' prices or two measurements. It compares the gap with the average of the two, so swapping them gives the same answer.
A change from a negative starting value is measured against its size without the sign, so a rise from −10 to −5 is an increase of 50%. A change from 0 has no percentage, because any rise from nothing is infinitely large.
Percentage points are different again: an interest rate that goes from 4% to 5% rises by 1 percentage point, which is a 25% increase in the rate.
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