Percent Change Calculator
See how much a value grew or shrank in percentage terms, along with the raw difference.
How to use the Percent Change Calculator
- Enter the original value.
- Enter the new value.
- Press Calculate. The result updates automatically as you type.
About the Percent Change Calculator
Percent change answers "by how much did this move, relative to where it started?" It is the standard way to report changes in prices, populations, test scores, website traffic or any measured quantity over time. Because the change is divided by the original value, the order matters: going from 50 to 65 is a 30% increase, but going from 65 back to 50 is only a 23.08% decrease.
That asymmetry is why a 50% loss needs a 100% gain to recover. When neither value is a natural "before," such as comparing two labs' measurements, use the percent difference instead; it divides by the average, so swapping the numbers gives the same answer.
Formula
Percent change = (New − Original) ÷ |Original| × 100
A positive result is an increase and a negative result is a decrease. The percent difference compares two values without treating either as the starting point:
Percent difference = |A − B| ÷ ((|A| + |B|) ÷ 2) × 100
Example calculation
Using the default values:
- Original value = 50
- New value = 65
the calculator returns:
- Percent change: 30%
- Direction: Increase
- Absolute change: 15
- Percent difference (vs. average): 26.087%
- New ÷ original (multiplier): 1.3
Frequently asked questions
How do I calculate percent increase?
Subtract the original value from the new value, divide by the original value, and multiply by 100. From 50 to 65: (65 − 50) ÷ 50 × 100 = 30%.
What is the difference between percent change and percent difference?
Percent change measures movement from a starting value. Percent difference compares two values on equal footing by dividing their gap by their average.
Why is the result undefined when the original value is zero?
Percent change divides by the original value, and division by zero has no meaning. Report the absolute change instead.
What is the difference between percent and percentage points?
If a rate rises from 4% to 5%, it went up 1 percentage point, but that is a 25% increase in the rate itself.
Last updated: · Category: Math calculators