MihsabaShare this free calculator
Send this tool to someone who needs the calculation.
How to use
Measure the increase or decrease from an old value to a new value relative to the starting value. The calculator shows signed percentage change, absolute change and direction so relative movement is not confused with the raw numerical difference.
- Enter the old or starting value.
- Enter the new or ending value.
- Calculate to see the percentage change, numerical difference and direction.
How it is calculated
Example
Example: moving from 200 to 250 is a +50 absolute change and +25% percentage change. Going back from 250 to 200 is -20%, because the starting base is different. Moving from 100 to 80 is a 20% decrease, but returning from 80 to 100 requires a 25% increase because the new base is 80. Likewise, increasing by 20% and then decreasing the result by 20% takes 100 to 120 to 96: an overall −4% change. Successive changes use different bases and cannot simply be added.
Important notes
If the old value is zero, a standard percentage change is undefined because the formula divides by the starting value. For a negative starting value, this calculator uses the absolute starting magnitude in the denominator so the sign more clearly represents direction.
Worked examples and interpreting results
Moving from 80 to 100 is a 25% increase because 80 is the starting value. Returning from 100 to 80 is a 20% decrease; reversing direction changes the reference value.
| Case | Calculation | Result |
|---|---|---|
| From 80 to 100 | (100 − 80) ÷ |80| × 100 | 25 % |
| From 100 to 80 | (80 − 100) ÷ |100| × 100 | -20 % |
| Change from 100 to 80 | (80 − 100) ÷ 100 × 100 | -20 % |
| Change when returning from 80 to 100 | (100 − 80) ÷ 80 × 100 | 25 % |
How to check the result
A zero starting value gives no finite percentage change under this formula. The calculator uses the absolute starting value in the denominator; for negative values, consider the numerical change and context before interpreting the percentage as growth.
Percentage change formula for increase and decrease
Subtract the old value from the new value, divide by the old value and multiply by 100. Positive changes are increases and negative changes are decreases relative to the old baseline.
- Increase from 100 to 125: (125−100)÷100×100 = +25%
- Decrease from 120 to 90: (90−120)÷120×100 = −25%
- No change from 50 to 50: (50−50)÷50×100 = 0%
Calculation caveat
When the original value is zero the usual percentage-change formula is undefined. Do not confuse change from an old baseline with symmetric percentage difference.
Related calculators
Frequently asked questions
Why does +50% followed by -50% not return to the start?
Because the two percentages use different bases. After the increase, the larger value becomes the base for the decrease.
What is the difference between percentage change and absolute change?
Absolute change is new minus old; percentage change compares that difference with the size of the starting value.
Can percentage change exceed 100%?
Yes. For example, moving from 50 to 125 is a 150% increase.
Is moving from 5% to 6% a 1% change?
It is an increase of one percentage point, but relative change is (6−5)÷5×100=20%. Enter 5 and 6 to calculate relative change between these rates.
How do I calculate a price decrease?
Enter the price before the decrease as old value and after it as new value. The result is negative: 150 to 120 gives −20%, a decrease of 20%.