Percentage Increase Calculator
Find the percentage change between two numbers, or raise or lower a number by a percentage. The same page covers percentage decrease.
Percentage change between two numbers
Enter a starting value and a new value to see the increase or decrease as a percentage.
Increase a number by a percentage
Example: add 15% to 200.
Decrease a number by a percentage
Example: take 25% off 80.
The percentage change formula
Percentage change = (New value − Old value) ÷ Old value × 100
Increased value = Old value × (1 + Percentage ÷ 100)
Decreased value = Old value × (1 − Percentage ÷ 100)
A positive result is an increase and a negative result is a decrease. The calculator labels it for you.
Worked examples
| Situation | Working | Result |
|---|---|---|
| 50 rises to 65 | (65 − 50) ÷ 50 × 100 | 30% increase |
| 80 falls to 60 | (60 − 80) ÷ 80 × 100 | 25% decrease |
| Add 15% to 200 | 200 × 1.15 | 230 |
| Take 25% off 80 | 80 × 0.75 | 60 |
Why up 50% then down 50% does not get you back
Each percentage is taken from a different starting point. Start with 100 and add 50% to reach 150. Taking 50% off 150 removes 75 and leaves 75, not 100. To get from 150 back to 100 you need a fall of 33.33%.
Percent versus percentage points
If an interest rate moves from 4% to 6%, it rose by 2 percentage points. As a percentage change it rose by 50%, because 2 is half of 4. Both statements are correct, but they mean different things, so check which one is being quoted.
Limits of this calculator
The starting value cannot be zero, because a percentage change from zero is undefined. This tool is designed for values of zero or more, such as prices, quantities and counts.
Frequently asked questions
How do I calculate percentage increase?
Subtract the old value from the new value, divide the result by the old value, then multiply by 100.
How do I reverse a percentage increase?
Divide the new value by 1 plus the percentage as a decimal. If a price rose 20% to 120, the original was 120 ÷ 1.20 = 100. The "X is Y% of what number" tool on the Percentage Calculator page does the same job.
Is percentage decrease calculated the same way?
Yes. The formula is identical and gives a negative number, which means the value went down.
Why does the calculator reject a starting value of zero?
Percentage change divides by the starting value, and you cannot divide by zero.
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Results are for general information only. The calculators are tested, but please double-check anything important before relying on it for financial, tax, legal or medical decisions.