Calculate the percentage change between a starting and final value — increase, decrease and absolute difference.
How is percentage change calculated?
The formula: change % = (final − initial) ÷ |initial| × 100.
Examples
- From 100 to 125: (125−100)÷100×100 = +25%
- From 125 to 100: (100−125)÷125×100 = −20% — not −25%! The base changed.
The common mistake
A 50% rise followed by a 50% drop does not return to the start: 100 → 150 → 75. Always know your base value.
When the initial value is 0, percentage change is mathematically undefined.
Frequently Asked Questions
Percent change vs percentage points?
Percent change is relative to the base; points are the absolute gap between two percentages. 10% → 12% is 2 points, which is a 20% change.
Why is change from 0 undefined?
Division by zero is undefined — any non-zero value is "infinitely" larger than zero.
How do I chain changes across periods?
Multiply the factors: two 10% rises are 1.1×1.1 = 21%, not 20%.