Percentage change calculator
Find the percent increase or decrease from an old value to a new one.
What is X% of Y?
X is what percent of Y?
Percentage change
Increase or decrease by a percent
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Percentage change formula
% change = (new − old) ÷ |old| × 100
Example: a price going from $80 to $100 is (100 − 80) ÷ 80 × 100 = 25% increase. Going back from $100 to $80 is a 20% decrease — the base changed, so the percentages differ.
Percentage change vs percentage points
If an interest rate rises from 4% to 5%, that’s a rise of 1 percentage point but a 25% increase in the rate.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. 20% of 250 = 250 × 20 ÷ 100 = 50.
How do I work out a percentage increase?
Subtract the old value from the new value, divide by the old value and multiply by 100.
How do I add sales tax?
Multiply the price by 1 plus the tax rate. For 13% HST in Ontario: $50 × 1.13 = $56.50.
How do I reverse a percentage?
Divide by 1 plus the rate. A $56.50 total including 13% tax had a pre-tax price of 56.50 ÷ 1.13 = $50.