Percent Change Calculator
Enter an old value and a new value to see the percent change between them. A positive answer is an increase and a negative answer is a decrease; the difference and the multiplier are shown too.
- Direction
- Increase
- Difference
- 20
- Multiplier (new ÷ old)
- 1.25 ×
Saved setups
Save a set of inputs you reuse — your usual rate, your loan, your room sizes — and load it back in one tap.
Your recent calculations
Results you calculate here are kept on this device so you can come back to them.
Formula
How to use it
- Enter the starting (old) value.
- Enter the ending (new) value.
- Read the percent change. The direction line tells you whether it is an increase or a decrease.
Worked examples
A price rises from 80 to 100
- Percent change
- 25%
- Direction
- Increase
- Difference
- 20
- Multiplier (new ÷ old)
- 1.25 ×
Sales fall from 250 to 200
- Percent change
- -20%
- Direction
- Decrease
- Difference
- -50
- Multiplier (new ÷ old)
- 0.8 ×
Increases and decreases do not cancel
A 25% rise followed by a 25% fall does not bring you back to where you started: 1.25 × 0.75 = 0.9375, so you end up 6.25% lower. A 50% loss needs a 100% gain to recover.
This is why the change from 80 to 100 is +25% but the change from 100 back to 80 is −20%. The amount is the same; the base it is measured against is not.
When the old value is zero or negative
Percent change from zero is undefined, because you cannot divide by zero — the calculator shows no result. For a negative starting value it divides by the absolute value, so the sign of the answer still tells you whether the number went up or down.
Questions people ask
What is the percent change from 80 to 100?
25%. The difference is 20, and 20 ÷ 80 = 0.25.
What is the percent change from 250 to 200?
−20%, a 20% decrease. The difference is −50, and −50 ÷ 250 = −0.20.
What is the difference between percent change and percent difference?
Percent change compares a new value with an old one, so order matters. Percent difference compares two values with no “before” and “after” by dividing by their average, so the order does not matter.