Percent Change Calculator
Find the percentage increase or decrease between two numbers, apply a percent change, or work backward to the original value. Results update as you type, and your numbers never leave this page.
Calculate percent change
Estimates only. This tool provides estimates for general calculation purposes.
Need a different kind of percentage? Try our Percentage Calculator for X% of Y, what percent X is of Y, and quick percent changes.
How percent change works
Percent change compares a new value to an old value as a percentage of the old value. The formula is:
percent change = ((new value - old value) / |old value|) x 100
A positive result is a percentage increase, a negative result is a percentage decrease. The old value sits in the denominator, so the starting point matters: the same dollar change can be a different percentage depending on where you started.
Worked examples
- A 25% increase. A price rises from $80 to $100. ((100 - 80) / 80) x 100 = +25%. The $20 increase is 25% of the starting price.
- A 20% decrease. A price falls from $100 to $80. ((80 - 100) / 100) x 100 = -20%. Notice the same $20 move is a smaller percentage here, because the starting value is larger.
- A raise. A salary goes from $50,000 to $56,000. ((56,000 - 50,000) / 50,000) x 100 = +12%.
Common questions
What if the starting value is zero?
Percent change is undefined when the old value is zero, because the formula divides by the old value. Going from 0 to anything is not a percentage you can compute; the tool says so plainly instead of guessing.
Is a 25% increase undone by a 25% decrease?
No. If $100 rises 25% to $125, a 25% decrease from $125 lands at $93.75, not $100. It takes a 20% decrease to return to the start, because the second percentage is measured against the larger number.
What is the difference between percent change and percentage points?
Going from 10% to 15% is a 5 percentage point move, but a 50% percent change relative to the starting 10%. The two answer different questions.
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