How to calculate percentage change
Subtract the original value from the new value, divide that difference by the absolute original value, then multiply by 100. A positive result is an increase; a negative result is a decrease.
Formula: ((new − original) ÷ |original|) × 100
Example
A price moving from $80 to $100 increased by $20. Dividing 20 by 80 gives 0.25, so the percentage increase is 25%.