Percentage Increase Calculator

Measure how much something has grown in percentage terms, or add a percentage to a starting value.

Percentage increase between two values

Percentage increase25%
Signed percentage change
+25%
Absolute change
20

Working

  1. Difference: 100 − 80 = 20
  2. Divide by the original value: 20 ÷ 80 = 0.25
  3. Multiply by 100: 25%

Increase a value by a percentage

250 increased by 12%280
Amount of increase
30

Working

  1. Increase amount: 250 × 12 ÷ 100 = 30
  2. New value: 250 + 30 = 280
  3. Shortcut: 250 × 1.12 = 280

The percentage increase formula

Percentage increase compares the size of the change with the original value — not the new one. That is why it matters which number you treat as the starting point.

increase % = (new − original) ÷ original × 100

new
the later or larger value
original
the starting value (must not be zero)

To go the other way and add a percentage to a value, multiply by (1 + p ÷ 100). A 12% increase is the same as multiplying by 1.12.

Worked example

A price rises from 80 to 100

  1. Change: 100 − 80 = 20
  2. Divide by the original: 20 ÷ 80 = 0.25
  3. Convert to a percentage: 0.25 × 100 = 25%

The price increased by 25%.

Increase 250 by 12%

  1. 12% of 250 = 0.12 × 250 = 30
  2. Add it on: 250 + 30 = 280

Or in one step: 250 × 1.12 = 280.

Common pitfalls

  • Increases and decreases are not symmetric. Going from 80 to 100 is a 25% increase, but going back from 100 to 80 is only a 20% decrease.
  • Consecutive increases compound. Two 10% rises give 1.1 × 1.1 = 1.21, a 21% total increase — not 20%.
  • Percentage points are different. A rate moving from 4% to 5% is a rise of 1 percentage point, but a 25% increase in the rate itself.

Typical uses

Comparing prices over time, measuring growth in visitors or sales, working out a pay rise, or checking how much a measurement has changed between two readings.

Common questions

What if the new value is smaller?

Then the change is a decrease. The calculator still shows the signed change (for example −20%); for decreases, the percentage decrease calculator words the result more naturally.

Why can’t the original value be zero?

Percentage change divides by the original value, and division by zero is undefined. Growth from zero has no meaningful percentage — you can only state the absolute change.