Percentage Calculator

Percentage Calculator

Common percentage formulas

Use this calculator for three everyday percentage questions: what percent one number is of another, what a percentage of a number equals, and how much a value increased or decreased. The basic formula is part / whole × 100. For example, 20 is 25% of 80 because 20 / 80 × 100 = 25.

For change over time, use (new value - old value) / old value × 100. If a price moves from 50 to 65, the increase is 15, and 15 / 50 × 100 = 30%. A drop from 65 to 50 is not -30%; it is about -23.08% because the starting value is now 65.

Percent vs percentage points

A move from 10% to 15% is a 5 percentage point increase, but it is a 50% relative increase. This matters in finance, polls, conversion rates, discounts, and tax comparisons. Use percentage points when comparing two rates, and percentage change when comparing the size of the movement relative to the starting value.

Quick FAQ

Can percentages be above 100? Yes. 120 is 150% of 80. Can they be negative? Yes, when the result represents a decrease or loss. Should I round? Round only after the final result if you need a clean displayed number.