Calculate percentage change
| Cell | Meaning | Example value |
|---|---|---|
| A2 | Old value | 100 |
| B2 | New value | 80 |
Formula
=(B2-A2)/ABS(A2)Expected result: -20%
Format the result cell as a percentage. A negative result means a decrease; A2 cannot be zero.
Percentage Change Calculator
Measure an increase or decrease from an old value to a new value, with the old value as the reference.
Percentage Change Calculator
Change from to =
How it works
Formula and steps
The formula shows how the percentage change calculator turns your inputs into the result. Use it to check the calculation, then follow the example steps to see each part of the math.
Formula & steps
Percentage change formula
C% = ((NV - OV) / |OV|) x 100
Use this when a value changes from an old value to a new value.
C%= Percentage changeNV= New valueOV= Old value|OV|= Absolute old value- 180 - 100 = -20
- 2-20 / 100 = -0.2
- 3-0.2 x 100 = -20%, or a 20% decrease
Worked examples
Example 1
A monthly budget changes from $100 to $80
- 1
Find the change
$80 - $100 = -$20
- 2
Divide by the old value
-$20 / $100 = -0.20
- 3
Convert to a percent
-0.20 x 100 = -20%, a 20% decrease
Example 2
Revenue changes from $80 to $100
- 1
Find the change
$100 - $80 = $20
- 2
Divide by the old value
$20 / $80 = 0.25
- 3
Convert to a percent
0.25 x 100 = 25% increase
Spreadsheet formulas
Calculate in Excel or Google Sheets
Enter the example values in the listed cells, then paste the formula into another cell. Excel and Google Sheets use the same formulas shown here.
Common uses
- Month-over-month or year-over-year comparisons
- Budget changes
- Performance tracking
- Growth and decline reports
Common mistakes
- Using percentage difference when you actually need old-to-new percentage change.
- Treating a negative result as an error instead of a decrease.
- Assuming a short-period percentage change is automatically an annual growth rate.
Percentage change guide
How to calculate percentage change
Percentage change compares a new value with a defined old value. Its sign shows direction: positive means growth and negative means decline.
Calculate old-to-new change
Subtract the old value from the new value, divide by the absolute old value, then multiply by 100. From 100 to 80, the result is -20%, meaning a 20% decrease.
Percentage change is directional
A move from 80 to 100 is a 25% increase, while returning from 100 to 80 is a 20% decrease. The reference value changes, so the percentages are not opposites of equal size.
Calculate percentage increase only →Use percentage difference for peer values
If neither value is old or new, use their average as a neutral reference instead of choosing one value as the denominator.
Compare two values symmetrically →FAQ
Yes. A negative result means the new value is lower than the old value.
No. Percentage change uses the old value as the reference. Percentage difference uses the average of both values.
Use the previous month as the old value and the current month as the new value. Subtract, divide by the absolute previous-month value, then multiply by 100.
No. It measures the total change between two values. Annualizing a multi-year change requires the time period and a compound annual growth rate calculation.
Change from zero is undefined. For a negative old value, this calculator divides by its absolute value so the sign shows direction, but movement across zero can make percentage interpretation misleading; report the actual values too.
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