How it works
The difference between the new and original values is divided by the original value, then multiplied by 100. Because the original value is the base of the comparison, swapping the two values does not give the same result.
To work through an example, take a value changing from 50 to 65: first find the difference (65 − 50 = 15). Then divide that difference by the original value (15 ÷ 50 = 0.3). Finally multiply by 100 to express it as a percentage (0.3 × 100 = 30%). This gives a 30% increase.
Unlike the Percentage Difference Calculator, which treats both values equally, percentage change is directional and depends on which value is the original. A fall uses the same formula but produces a negative result, as shown in the examples.
Formula: Percentage change = (new − original) ÷ original × 100
Examples
An increase
From 50 to 65 is a change of ((65 − 50) ÷ 50) × 100 = 30%.
A decrease
From 100 to 80 is a change of ((80 − 100) ÷ 100) × 100 = −20%.
A small increase with decimals
From 10.00 to 10.50 is a change of ((10.50 − 10.00) ÷ 10.00) × 100 = 5%.
A large decrease
From 200 to 50 is a change of ((50 − 200) ÷ 200) × 100 = −75%.
Common uses
- Checking how much a price has risen or fallen over time.
- Measuring performance changes like test scores or completion rates.
- Tracking changes in quantities such as stock levels or distances.
- Comparing before and after measurements in simple experiments.
Things to keep in mind
- Percentage change is directional and uses the original value as its base — it is not the same calculation as percentage difference, which treats both values symmetrically and does not care which one came first. See the Percentage Difference Calculator for that version.
- Percentage change cannot be calculated from an original value of zero, since there is nothing to compare the change to.