FORMULAS

The math behind every answer.

Six formulas cover nearly every percentage problem. Each calculator above applies one of these — and shows you exactly how.

Percentage of a number

result = number × (percent ÷ 100)25% of 200 = 200 × 0.25 = 50

X is what percent of Y

percent = (part ÷ whole) × 10050 ÷ 200 × 100 = 25%

Percentage change

change = ((new − old) ÷ |old|) × 100(150 − 120) ÷ 120 × 100 = 25% increase

Percentage difference

diff = |a − b| ÷ ((a + b) ÷ 2) × 100|40 − 60| ÷ 50 × 100 = 40%

Increase by a percentage

result = number × (1 + percent ÷ 100)80 increased by 15% = 80 × 1.15 = 92

Decrease by a percentage

result = number × (1 − percent ÷ 100)80 decreased by 15% = 80 × 0.85 = 68