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Measure the percentage increase or decrease between two values—prices, salaries, website traffic, portfolio balances. Enter the old and new value and get the signed change.

Percentage change calculator

Enter the old and new value to get the percentage change between them. Change % = (new − old) ÷ old × 100 — positive means an increase, negative a decrease.

Increase: 28%

Absolute change: 70

Formula

change % = (new − old) ÷ old × 100

Example: From 250 to 320: (320 − 250) ÷ 250 × 100 = 28% increase.

Prices, salaries, and traffic over time

Percentage change answers “how big was the move relative to where it started”: rent going from 1,200 to 1,320 is a 10% increase; a portfolio going from 8,000 to 7,200 is a 10% drop. The same absolute change means very different things at different starting points, which is exactly what this measure captures.

Remember the asymmetry: a 50% drop needs a 100% gain to get back to even. That is why sequences of gains and losses cannot simply be added — each percentage applies to a different base.

How to use Percentage change

  1. Enter the old (starting) value.
  2. Enter the new (current) value.
  3. Read the percentage change and the absolute difference.

Example: From 250 to 320 is a 28% increase; from 320 back to 250 is a 21.9% decrease.

Frequently asked questions

Why is the percentage different going up versus coming back down?
Because the base changes. Going from 250 to 320 divides the change by 250, but going from 320 to 250 divides by 320. That is also why a 50% loss needs a 100% gain to recover.
What if the old value is zero?
Percentage change from zero is mathematically undefined—any increase from nothing is infinite in percentage terms. Report the absolute change instead.

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