Percentage Increase Calculator
How much a value grew, as a percentage of where it started.
The formula
increase % = (final - start) / start × 100
From 40 to 50: (50 - 40) / 40 × 100 = 25%. The starting value is always the base, which is why going from 50 back down to 40 is not -25% but -20%.
Increases don't cancel out
A 25% rise followed by a 25% fall does not return to the start: 40 → 50 → 37.5. Each step uses its own base. This asymmetry is why a stock that drops 50% needs a 100% gain to recover, and why chaining percentages should always be done by multiplying factors (1.25 × 0.75 = 0.9375, a net 6.25% loss).