Percentage Change Calculator
Enter an old and a new value to see the percentage increase or decrease.
How it works
- Enter the original value.
- Enter the new value.
- Read the percentage increase or decrease and the difference.
Frequently asked questions
How is percentage change calculated?
Percentage change = (new − original) ÷ original × 100. Going from 80 to 100 is a 25% increase; going from 100 to 80 is a 20% decrease.
What is the difference between percentage change and percentage difference?
Percentage change measures change from a starting point. Percentage difference compares two values without a direction, dividing by their average, which suits comparing two measurements.
Why can't the original value be zero?
Dividing by zero is undefined — any increase from zero is infinite in percentage terms. Describe such changes in absolute numbers instead.
Is a 50% drop undone by a 50% rise?
No. After a 50% drop, 100 becomes 50, and a 50% rise only brings it back to 75. You would need a 100% rise to recover.
Measure change as a percentage
Percentage change puts differences on a common scale, so you can compare a price rise, a traffic drop or a salary increase fairly regardless of the size of the original numbers.
Increase vs decrease
A positive result is an increase and a negative result a decrease. Remember that percentage changes aren't symmetrical: a 20% fall followed by a 20% rise leaves you 4% below where you started.