Percentage Change Calculator
Calculate percentage increase or decrease between two values, or work backwards to find the original value before a percentage change was applied.
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What's the key thing to understand about The Formula?
Percentage change = ((New Value minus Original Value) divided by Original Value) times 100. A positive result indicates an increase; negative indicates a decrease. Example: a price rises from £80 to £96: change = ((96-80)/80) × 100 = 20% increase. A salary falls from £42,000 to £38,000: change = ((38,000-42,000)/42,000) × 100 = -9.5% decrease. The formula always uses the original value as the denominator — this is why a 50% fall followed by a 50% rise does not return to the original: a 50% fall
What do I need to know about Common Applications?
Price inflation, salary increases, investment returns, population growth, test score changes, statistical comparisons. Any time you want to know 'how much has this changed relatively?'
What's the difference between Percentage Points and Percentage Change?
If a tax rate rises from 20% to 25%, that's a 5 percentage point increase but a 25% change. These are different and frequently confused — always specify which you mean in formal contexts.
What do I need to know about Percentage Change in Context?
Percentage change requires careful interpretation. A 50% fall followed by a 50% rise does not return to the original value: 100 falls 50% to 50, then rises 50% to 75 — a 25% net loss. The arithmetic mean of percentage changes is misleading for cumulative performance; the geometric mean (CAGR) is correct for multi-period return calculation. Share prices: a stock that drops 50% requires a 100% gain to return to its starting price — asymmetric recovery that catches many investors by surprise when estimating how much a loss needs to be recovered before breaking even.