🔄 Percentage Change Calculator
Calculate the percentage increase or decrease between an old value and a new value.
How Percentage Change Is Calculated
The percentage change formula is ((New Value - Old Value) / Old Value) × 100. A positive result indicates an increase, while a negative result indicates a decrease. For example, if a stock price rises from $50 to $60, the percentage change is ((60 - 50) / 50) × 100 = 20% increase. If the price falls from $50 to $40, the change is ((40 - 50) / 50) × 100 = -20% decrease.
Percentage change is used extensively in finance to measure investment returns, in business to track sales growth or decline, and in economics to report inflation rates and GDP growth. It is also commonly used in academic settings to evaluate test score improvements and in health sciences to measure changes in patient metrics like weight or blood pressure.
Important Caveats
Be aware that percentage change is relative and can be misleading when the starting value is very small. A change from 1 to 3 is a 200% increase but might not be significant in absolute terms. Also note that calculating the reverse change does not give the same percentage: a 50% increase from $100 to $150 requires a 33.3% decrease to return to $100.