How to use
Enter the old value and the new value. The calculator shows the percentage change, its direction (increase or decrease), the difference and the ratio between the two values.
Formula
change = (new − old) × 100 / old
The percentage is always calculated from the original (old) value.
Examples
- A price goes up from $80 to $100 — that’s +25%.
- A price goes down from $100 to $80 — that’s −20%, not −25%, because the base is different.
- A salary rises from $50,000 to $56,000 — +12%.
- An item goes from $1,200 to $1,500 (+25%) and then back to $1,200 — that’s −20%.
FAQ
Why doesn’t a 50% rise followed by a 50% drop get me back to where I started? Because each percentage is taken from a different number: 100 + 50% = 150, but 150 − 50% = 75.
Can I calculate a change from zero? No — a percentage change from zero is undefined, since you can’t divide by zero. The calculator shows no result in that case.
Is “25% more” the same as “1.25 times”? Yes, both mean the new value is 125% of the old one. The ratio field shows exactly that.
How do I add a percentage to a number? Use the percent increase and decrease calculator.