Percentage Change Calculator tells you how much a value has increased or decreased as a percentage of its original value. Enter the original (old) value and the new value, and it returns the percentage change — positive for an increase, negative for a decrease. Useful whenever you need to compare a metric before and after a change: website traffic, revenue figures, stock prices, test scores, or benchmark results between two runs.
The formula is: percentage change = ((new value − original value) ÷ |original value|) × 100. For example, if monthly traffic goes from 8,400 to 10,500 visits: ((10,500 − 8,400) ÷ 8,400) × 100 = 25% increase. If revenue drops from $50,000 to $40,000: ((40,000 − 50,000) ÷ 50,000) × 100 = −20%, meaning a 20% decrease.
Percentage change = ((New − Old) ÷ |Old|) × 100. Subtract the original from the new value, divide by the absolute value of the original, then multiply by 100. A positive result is an increase; a negative result is a decrease. The absolute value in the denominator ensures the sign of the result reflects the direction of change, not the sign of the original number.
These are frequently confused in reports. If a conversion rate rises from 4% to 6%, the percentage point change is +2 (6 − 4). But the percentage change is +50% ((6 − 4) ÷ 4 × 100). Always specify which you mean — reporting a 50% improvement when conversion moved only 2 points is technically correct but often misleading.
Yes. A value doubling is a 100% increase. Tripling is 200%. A metric growing from 10 to 1,000 is a 9,900% increase. There is no upper bound — percentage change can be arbitrarily large for values growing from a small base.
Percentage change is mathematically undefined when the original is 0, because the formula divides by the original value. If you are measuring growth from zero to any positive number, the increase is technically infinite. In practice, report the absolute increase instead — or choose a different baseline period.
Use the same formula. A negative result is a percentage decrease. For example, a price dropping from $80 to $60: ((60 − 80) ÷ 80) × 100 = −25%, meaning a 25% decrease. The magnitude of the negative number is the decrease percentage.
Percentage increase and percentage decrease are both types of percentage change. "Percentage change" covers both directions — the sign of the result tells you the direction. A positive value is an increase; a negative value is a decrease.
Tool workspace
Free percentage change calculator online — find the percentage increase or decrease between any two values. Shows the formula with a worked example. No login.
Input
Previous: 100, New: 120
Output
20% increase
