How to Calculate Percentage Increase
Percentage increase = (new − original) ÷ original × 100.
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Formula and worked example
Percentage increase = (new − original) ÷ original × 100
From 80 to 100: the increase is 20. Divide 20 by the original 80 and multiply by 100 = 25%.
Apply a percentage increase
Multiply by 1 + p/100. Increasing $120 by 15% gives 120 × 1.15 = $138. To work backward, divide by that multiplier.
Common mistake
Use the original value as the baseline for relative change. A percentage calculation can give a different answer when the denominator changes.
Related percentage guides
Sources & methodology
The formulas are displayed so the result can be checked manually. NIST defines the percent symbol as representing 0.01. The UK Office for National Statistics defines a percentage point as the difference between percentages.