The three percentage questions people actually ask, each answered as you type.
Results update as you type.
X% of Y = X ÷ 100 × Y. X is what % of Y = X ÷ Y × 100. % change = (B − A) ÷ |A| × 100.
A 25% rise then a 25% fall doesn't bring you back: 80 up 25% is 100; 100 down 25% is 75. The second change works from a bigger base, which is why a share that falls 50% needs a 100% gain to recover.
A rate going from 4% to 5% rose by one percentage point — and by 25 percent.
Subtract the old value from the new one, divide by the old value, multiply by 100. From 80 to 100: (100 − 80) ÷ 80 × 100 = 25%.
Percentage points are the plain difference between two percentages; percent change is that difference relative to the starting value.