Percentage Increase Calculator
Why use this calculator
Percentage change comes up constantly — comparing prices, salaries, test scores, or year-over-year metrics — but it's easy to get the direction or the formula wrong, especially when the original value is negative or zero. This calculator handles those edge cases explicitly instead of silently producing a wrong number.
Enter both values to see the result.
How percentage increase works
The formula is:
percentage change = (new value - original value) / |original value| × 100
Using the absolute value of the original value in the denominator keeps the sign of the result meaningful (positive = increase, negative = decrease) even when the original value itself is negative.
Common mistakes
- Dividing by the new value instead of the original. The percentage change is always relative to where you started, not where you ended up.
- Forgetting the zero case. If the original value is 0, percentage change is undefined — there's no way to express "increase from nothing" as a percentage.
- Confusing percentage change with percentage points. These are different measurements and mixing them up is a common source of misleading statistics.
Frequently asked questions
- How do you calculate percentage increase?
- Subtract the original value from the new value, divide the result by the original value, then multiply by 100. For example, going from 50 to 65 is (65 - 50) / 50 * 100 = 30% increase.
- What does a negative result mean?
- A negative percentage means the value decreased rather than increased. For example, going from 100 to 80 gives -20%, meaning a 20% decrease.
- What happens if the original value is zero?
- Percentage change is mathematically undefined when the original value is zero, because the formula divides by that value. This calculator will show an error instead of a misleading number in that case.
- Is percentage increase the same as percentage points?
- No. If a rate goes from 10% to 15%, that's a 5 percentage point increase, but a 50% relative (percentage) increase, since (15-10)/10*100 = 50%. This calculator computes the relative percentage change, not the percentage-point difference.