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EVERYDAY MATH, MADE SIMPLE
Percentage change calculator
From then to now. See exactly how much a number has changed.
YOUR RESULT
Percentage increase
25%
(100 − 80) ÷ 80 × 100 = 25%
Calculated instantly. Rounded to 6 decimal places.
Try an example:
✓ Always free⌁ No sign-up◈ Calculated on your device
01
How to calculate percentage change
Percentage change compares the difference between two values with the original value. A positive answer means an increase, and a negative answer means a decrease.
The formula
(New − Original) ÷ Original × 100-
1
Find the difference
If a value goes from 80 to 100, subtract 80 from 100 to get 20.
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2
Divide by the original value
20 ÷ 80 = 0.25. Always use the starting value as the denominator.
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3
Convert to a percentage
0.25 × 100 = 25%. The value has increased by 25%.
02
A change you can put into context
A lower weekly total
Going from 200 to 150 is a decrease of 25%.
A longer session
Moving from 45 to 60 minutes is an increase of about 33.33%.
03
Percentage change examples
Even the same absolute difference can represent a different percentage when the starting value changes.
| Original | New | Difference | Change |
|---|---|---|---|
| 50 | 75 | 25 | +50% |
| 80 | 100 | 20 | +25% |
| 100 | 80 | -20 | −20% |
| 200 | 150 | -50 | −25% |
| 40 | 40 | 0 | 0% |
| 50 | 0 | -50 | −100% |
04
A few common questions
What happens if the original value is zero?
Percentage change from zero is undefined because the formula would divide by zero. State the absolute change instead. For example, going from 0 to 20 is an increase of 20 units, but not a finite percentage increase.
Can I use negative starting values?
This calculator accepts a positive original value and a non-negative new value. Percentage change involving negative values can be misleading: moving from −10 to −5 is an improvement, but the standard signed-denominator formula gives −50%. Describe the absolute change or choose a method appropriate to your context.
Why does a 50% decrease need a 100% increase to recover?
After 100 falls by 50%, the new value is 50. Adding 50 back is now an increase of 100% of the smaller starting value. Percentage increases and decreases are measured against different bases.
Is percentage change the same as percentage difference?
No. Percentage change uses a specific starting value. A common percentage difference formula instead divides the absolute difference between two positive values by their average. It is useful when neither value is the starting point.
What if the percentage itself changes?
A rate moving from 20% to 30% has risen by 10 percentage points, or by 50% relative to the original rate. Enter 20 and 30 here to find the relative change.