% Percentage Calculator

Three types: what is X% of Y, X is what % of Y, and % change between numbers

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Types of Percentage Calculation

What is X% of Y? — multiply Y by X/100. Example: 20% of 350 = 350 × 0.20 = 70.

X is what percentage of Y? — divide X by Y and multiply by 100. Example: 75 out of 300 = (75 ÷ 300) × 100 = 25%.

Percentage change — subtract the old value from the new, divide by the old, multiply by 100. Example: from 80 to 100 = ((100−80) ÷ 80) × 100 = 25% increase.

Common Uses

  • Discounts: A 30% discount on £250 = £250 × 0.30 = £75 off
  • VAT: 20% VAT on £100 net = £20 VAT, £120 gross
  • Pay rises: A 5% rise on £35,000 = £35,000 × 0.05 = £1,750 increase
  • Exam scores: 72 out of 90 = (72 ÷ 90) × 100 = 80%