Everyday calculations
Percentage Change Calculator
Enter an old value and a new value to see the percentage increase or decrease between them, and the actual difference.
It also shows something most calculators skip: the change you would need to get back to the old value. It's never the same percentage, and this is where a lot of people get caught out.
Calculator
Fill in the boxes above and your answer appears here.
Worked examples
Real numbers, worked out by the same calculator. Press “Use these numbers” to try one above.
From 50 to 75
- Percentage increase
- 50%
- Difference
- 25
- Fall needed to get back
- 33.33%
Going from 50 to 75 is an increase of 50%. To get back to 50 you'd need a decrease of 33.33%, which isn't the same number.
From 80 to 60
- Percentage decrease
- -25%
- Difference
- -20
- Rise needed to get back
- 33.33%
Going from 80 to 60 is a decrease of 25%. To get back to 80 you'd need an increase of 33.33%, which isn't the same number.
From 120 to 90
- Percentage decrease
- -25%
- Difference
- -30
- Rise needed to get back
- 33.33%
Going from 120 to 90 is a decrease of 25%. To get back to 120 you'd need an increase of 33.33%, which isn't the same number.
The formula
Percentage change = (new value − old value) ÷ old value × 100.
A positive answer is an increase and a negative answer is a decrease. From 50 to 75: (75 − 50) ÷ 50 × 100 = 50% increase. From 80 to 60: (60 − 80) ÷ 80 × 100 = −25%, a 25% decrease.
Why +50% then −50% doesn't get you back
Start with 100. Increase it by 50% and you have 150. Now take 50% off and you have 75, not 100. The second percentage is applied to a bigger number.
To undo a 50% rise you need a fall of 33.33% (150 → 100). To undo a 25% fall you need a rise of 33.33%. The calculator above shows this “way back” figure for any change.
Percentage change vs percentage difference
Percentage change compares a new value with an old one, so the order matters. Percentage difference compares two values that are equally important, like two competing quotes, and uses their average as the base. This calculator does percentage change: use it when one number came first.
Frequently asked questions
How do I calculate percentage increase?
Subtract the old value from the new value, divide by the old value, and multiply by 100. From 50 to 75 that is 25 ÷ 50 × 100 = 50%.
How do I calculate percentage decrease?
Use the same formula. If the answer is negative, it's a decrease. From 80 to 60: (60 − 80) ÷ 80 = −0.25, so a 25% decrease.
Can a percentage increase be more than 100%?
Yes. If a value doubles, that's a 100% increase, and if it triples, it's a 200% increase. A decrease can't be more than 100% unless the value goes below zero.
Why can't I calculate a percentage change from zero?
The formula divides by the old value, and you can't divide by zero. A rise from nothing has no percentage. Describe it as an absolute change instead.
What's the difference between percentage points and percent?
Going from 10% to 12% is a rise of 2 percentage points, but a 20% increase in the rate itself (2 ÷ 10).
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- MoneyDiscount CalculatorWork out a sale price after a percentage off, find the discount from two prices, or reverse it to get the original price. Handles two discounts.
Formulas tested against hand-worked answers. Last reviewed 29 September 2026. These calculators do arithmetic only; they are not financial, tax or legal advice.