Percentage calculator

How it works

Percent means “per hundred”, so every one of these is the same move: turn the percentage into a fraction by dividing by 100, then multiply or divide as the question requires. The one people get wrong is percent change, because it matters which number is the baseline — going from 50 to 75 is a 50% increase, but going back from 75 to 50 is a 33.3% decrease, not another 50%. The change is always measured against where you started, not where you ended up. That asymmetry is also why a 50% loss needs a 100% gain to break even.