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Percentage Change Calculator
Calculate the percentage increase or decrease between any two values.
Increase & Decrease
Colour-coded results: green for gains, red for losses
Step-by-Step Formula
See the exact calculation broken down
Absolute & Multiplier
Absolute change and multiplier alongside percentage
Calculate Percentage Change
Enter the original and new values to find the percentage increase or decrease.
How to Calculate Percentage Change
The Formula
The absolute value of the old number is used as the denominator to handle negative starting values correctly. A positive result means increase, negative means decrease.
Worked Examples
- Stock: £50 to £65: ((65-50)/50) x 100 = 30% increase
- Rent: £1,200 to £1,080: ((1080-1200)/1200) x 100 = 10% decrease
- Revenue: £0 to £500: Change from zero is undefined (infinite)
Percentage Change in Finance and Investing
Stock Price Movements
Returns are always expressed as percentage changes. A stock going from £10 to £12 is a 20% gain. Going from £12 back to £10 is a 16.7% loss — not 20%. This asymmetry is fundamental to understanding investment risk.
Economic Indicators
GDP growth, inflation, employment, and trade data are all reported as percentage changes. Quarter-on-quarter, year-on-year, and month-on-month comparisons each tell different stories about the same underlying data.
How to Use This Calculator
Enter Original Value
The starting number (before the change).
Enter New Value
The ending number (after the change).
See the Change
Percentage, absolute change, and multiplier.
Common Percentage Change Pitfalls
- Asymmetry of losses. A 50% loss requires a 100% gain to recover. A 33% loss needs 50%. The deeper the loss, the harder the recovery — this is why risk management is more important than maximising returns.
- Base effect. Small starting numbers produce large percentage changes. A stock going from £1 to £2 is a 100% gain, but from £100 to £101 is only 1% — even though both gained £1.
- Compounding vs single-period. Three consecutive 10% gains do not equal 30%. They equal 1.1 x 1.1 x 1.1 = 33.1%. Compounding makes repeated percentage changes non-additive.
- Percentage points vs percentages. An interest rate from 2% to 3% is 1 percentage point but 50%. Always clarify which measure you mean.
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