How to Calculate Percentage Change
Percentage change tells you how much something went up or down compared with where it started.
The formula
Percent change = (new value − old value) ÷ old value × 100. If the result is positive, it is an increase. If it is negative, it is a decrease.
Step by step
- Subtract the old value from the new value.
- Divide the result by the old value.
- Multiply by 100 to turn it into a percentage.
Example: a price increase
A price goes from $80 to $100. The change is $20. Divide by $80 to get 0.25, and multiply by 100 for a 25% increase.
Example: a decrease
A price falls from $100 to $80. The change is −$20. Divide by $100 to get −0.20, so it is a 20% decrease. The percentages differ because each uses a different starting value.
Why up 20% and down 20% does not return you to the start
Start with $100 and add 20% to reach $120. Now take 20% off $120, which is $24, to reach $96. You end up 4% below where you started.
Percent vs percentage points
If a rate moves from 5% to 8%, it rises by 3 percentage points. The percent change is 3 ÷ 5 × 100 = 60%. News articles mix these up often, so check which one is meant.
Try it
Use the Percentage Change Calculator to check your numbers, or the Percentage Calculator to find a percent of any number. For store prices, see the Discount Calculator.