Find X% of a number, or what percent one number is of another.
Percentage Increase/Decrease Calculator
Work out percentage change, apply an increase or decrease, or reverse one to find the original value.
Runs in your browser — nothing you enter is sent to our servers
How it works
- Change between two values: (new − original) ÷ |original| × 100.
- Apply a change: new = original × (1 ± percentage ÷ 100).
- Reverse a change: original = new ÷ (1 ± percentage ÷ 100).
The multiplier is the number you would multiply by to get from the original to the new value. Multipliers make chained changes easy: multiply them together.
Example
Monthly sales rose from R80,000 to R100,000: (100,000 − 80,000) ÷ 80,000 × 100 = 25% increase, multiplier 1.25.
A supplier says prices are going up 8% and your current cost is R250: 250 × 1.08 = R270. A price tag shows R270 after an 8% increase? 270 ÷ 1.08 = R250 originally.
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 80 to 100: (100 − 80) ÷ 80 × 100 = 25% increase.
Why doesn’t a 20% increase followed by a 20% decrease get me back to the start?
Each percentage applies to a different base. 100 + 20% = 120, but 20% of 120 is 24, so 120 − 24 = 96. Successive changes multiply: 1.2 × 0.8 = 0.96.
How do I find the original price before an increase?
Divide the new value by (1 + percentage ÷ 100). If a price is R115 after a 15% increase, the original was 115 ÷ 1.15 = R100. Use the “Reverse a change” mode.
What is the difference between percentage change and percentage points?
If an interest rate moves from 10% to 12%, it rose by 2 percentage points — but by 20% in relative terms (2 ÷ 10). This calculator shows relative change.
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