plainlyPercentage change calculator
From then to now.
See how much changed, in numbers and percent.
Percentage change
25%
120 → 150: 30 increase.
(150 − 120) ÷ 120 × 100 = 25%
A positive percentage is an increase; a negative percentage is a decrease. Rounded to four decimal places.
Free to use. No account. Your numbers stay in this tab.
How to calculate
percentage change
Subtract the old value from the new value. Divide that difference by the old value, then multiply by 100. This percentage change calculator shows both the relative change and the absolute difference so you can see the scale of the change.
Percentage change = (new value − old value) ÷ old value × 100
For example, a price moving from 120 to 150 rises by 30. Relative to the original 120, that is a 25% increase. If it moves from 150 back to 120, the decrease is 20%, because the starting value is now 150.
Increase, decrease, or no change
With a positive old value, a positive result means an increase and a negative result means a decrease. Identical nonzero values give 0%. Enter decimal values or correctly grouped numbers such as 1,200.50; use the same units for both inputs.
What happens with a zero or negative old value?
A zero starting value makes relative percentage change undefined: the formula would divide by zero. The calculator still shows the absolute difference. Even a move from 0 to 0 has no defined relative percentage under this formula.
Negative starting values are allowed, but the signed percentage can be counterintuitive. From −100 to −50, the number increases by 50 while the standard formula returns −50%. For those inputs, the tool labels the signed result and shows the numeric direction separately instead of presenting the percentage sign as growth.
One change.
Two ways to read it.
Percentage change versus percentage points
If a rate rises from 10% to 15%, it has risen by 5 percentage points. Its relative percentage change is 50%: (15 − 10) ÷ 10 × 100. The units matter when describing the answer.
Percentage change versus percentage difference
Percentage change uses an old value as the baseline. Percentage difference compares two values without choosing a starting point, usually using their average as the denominator. Use change for before-and-after comparisons; do not treat the two formulas as interchangeable.
| Old | New | Change |
|---|---|---|
| 80 | 100 | +25% |
| 100 | 80 | −20% |
| 50 | 50 | 0% |
| 20 | 0 | −100% |
For positive starting values, the formula follows the percentage change explanation from Math Is Fun. Results use ordinary browser number precision and round to four decimal places; extremely small nonzero results are labelled rather than rounded to zero.
Good questions.
Straight answers.
Can I use this as a percentage increase calculator?
Yes. Enter the original amount as the old value and the larger amount as the new value. For positive starting values, the answer shows the percentage increase.
How do I calculate a percentage decrease?
Enter the starting amount followed by the smaller new amount. From 200 to 150, the signed result is −25%, which means a 25% decrease.
Why does swapping values give a different percentage?
The old value is the denominator. Swapping changes that baseline, so a 25% increase is reversed by a 20% decrease, not another 25%.
Can a percentage increase be greater than 100%?
Yes. Going from 10 to 30 is a 200% increase. The new value is three times the old value, while the increase itself is twice the old value.
Are my numbers saved?
No. Calculations happen in this tab without uploading your numbers or saving them to website storage. Reloading restores the example.
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