A percentage increase calculator finds how much a value has grown or shrunk as a percent. Enter the original value and the new value to get the percent change, or enter a value and a percent to increase or decrease it.
Use it for price changes, grades, populations, wages and any before-and-after comparison. A positive result is an increase and a negative result is a decrease.
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How percentage increase is calculated
The percent change formula
Subtract the original value from the new value, divide by the original, and multiply by 100.
percent change = (new − original) ÷ original × 100
Increasing a number by a percent
Multiply the value by 1 plus the percent as a decimal. To increase 200 by 12.5%, multiply by 1.125.
new value = original × (1 + percent ÷ 100)
Decreasing a number by a percent
Multiply by 1 minus the percent as a decimal. Decreasing 250 by 15% means multiplying by 0.85.
new value = original × (1 − percent ÷ 100)
Worked examples
Example 1: percent increase
A score rises from 80 to 92. The change is 12, and 12 ÷ 80 = 0.15, so the increase is 15%.
Example 2: percent decrease
A price falls from 100 to 60. The change is −40, and −40 ÷ 100 = −0.4, so the price dropped by 40%.
Example 3: increase a value by a percent
Increase 200 by 12.5%. The increase is 200 × 0.125 = 25, so the new value is 225.
Example 4: decrease a value by a percent
Decrease 250 by 15%. The decrease is 250 × 0.15 = 37.5, so the new value is 212.5.
Why a rise and a fall are not symmetric
A 25% increase on 100 gives 125, but falling back to 100 needs a drop of 25 ÷ 125 = 20%, not 25%. The calculator shows the percent change needed to return to the original.
Frequently asked questions
How do you calculate percentage increase?
Subtract the old value from the new value, divide by the old value, then multiply by 100.
How do you calculate percentage decrease?
Use the same formula. A negative answer means a decrease, for example from 100 to 60 is −40%.
What is the difference between percent and percentage points?
Percentage points compare two percents by subtraction, so going from 10% to 15% is a rise of 5 percentage points but a 50% increase.
Why can’t the original value be zero?
The formula divides by the original value, and a percent change from zero is undefined.
How do I add a percent to a number?
Multiply the number by 1 plus the percent as a decimal. For 15%, multiply by 1.15.