A positive result is an increase
From 80 to 100, the amount rises by 20. Divide 20 by the original 80 and multiply by 100: the increase is 25%.
Percentage change calculator
Local calculationCompare your original and new values
Enter values in the same units, without currency symbols.
Example answer
25%
Increase
Amount changed
+20
Same units as your inputs
From 80 to 100 is a 25% increase.
Displayed results use your chosen decimal precision.
See the calculation
(100 − 80) ÷ 80 × 100 = 25%
100 − 80 = 20
Live resultsNo sign-upNumbers stay in your browser
Understand the result
How to calculate percentage change
Percentage change compares a new value with an original value. Subtract the original from the new value, divide that difference by the original, then multiply by 100.
Percentage change = (new − original) ÷ original × 100
Amount changed = new − original
A negative result is a decrease
From 100 to 80, the amount falls by 20. Divide −20 by the original 100 and multiply by 100: the percentage change is −20%, a 20% decrease.
Zero means no relative change
From 80 to 80, the amount changed is 0 and the percentage change is 0%. The original value must still be greater than zero.
Try it with familiar numbers
Percentage increase and decrease examples
Choose an example to load the original and new values into the calculator. Values should use the same units and time period.
Salary
40,000 to 46,000
The amount increases by 6,000. Using 40,000 as the original value gives a 15% salary increase.
Try the salary increasePrice
250 to 200
The price decreases by 50. Dividing −50 by the original price of 250 gives a 20% decrease.
Try the price decreaseSales
1,200 to 1,500
Sales increase by 300, or 25%. Compare equivalent periods, such as two full months, to make the change meaningful.
Try the sales increaseNo change
80 to 80
Both values are equal. The amount changed and the percentage change are both 0.
Try equal valuesCheck the starting point
Why swapping the values changes the percentage
The original value is the denominator. An increase from 80 to 100 is 25%, but a decrease from 100 to 80 is 20%. The absolute amount is 20 in both cases; the baseline is different. Use Swap in the calculator to compare the two directions.
Change versus difference
Use percentage change when there is a clear original value. Percentage difference uses the average of two non-negative values when neither is the baseline. Comparing 80 and 100 that way gives about 22.22%.
Percent versus percentage points
A rate moving from 20% to 25% rises by 5 percentage points. Relative to the original rate of 20%, it is a 25% increase. The two descriptions answer different questions.
A fall and recovery use different bases
If 100 falls by 20% to 80, returning from 80 to 100 requires a 25% increase. Adding the percentages would miss the change of baseline.
Method and limits
Percentage change calculator questions
Check the baseline, units and displayed precision before using a result.
What if the original value is zero?
The standard formula divides by the original value. Division by zero is undefined, so this calculator shows an error instead of inventing a percentage. For example, a move from 0 to 100 has an absolute increase of 100, but no defined percentage change using this formula. This also applies to 0 to 0.
Can I use a negative original value?
This tool requires a positive original value. Negative baselines can be interpreted using different conventions, including dividing by the absolute original value. Those conventions answer different questions, so this tool does not silently choose one.
Can the new value be zero or negative?
Yes, if the original is positive. From 100 to 0 is a 100% decrease. From 100 to −50 is a percentage change of −150%, a 150% decrease. Decide whether negative values make sense for what you are measuring.
How do I add or subtract a percentage from an amount?
This calculator measures change between two values you already know. To increase an amount by 15%, multiply it by 1.15. To decrease it by 15%, multiply it by 0.85. That is a different operation from measuring percentage change.
What does the decimal setting do?
Choose up to 0, 2, 4 or 8 decimal places for displayed results. The original inputs are not rounded before calculation. A very small non-zero change may display as approximately zero; a note then shows approximate values. This tool uses ordinary browser number arithmetic, not arbitrary-precision decimal arithmetic.
Are my values saved or sent for calculation?
The calculation runs in this page in your browser. No account is needed, and this tool does not store a calculation history. Copy answer uses your clipboard only when you select that button. Reloading resets the example.