Percentage Calculator

Divide the part by the whole, then multiply by 100. Example: 45 out of 180 = (45 ÷ 180) × 100 = 25%. This is the most common percentage calculation in everyday life.

Percent change = ((New Value − Old Value) ÷ |Old Value|) × 100. Example: from $50 to $65 = ((65 − 50) ÷ 50) × 100 = +30% increase. From $65 to $50 = −23.1% decrease.

Multiply the percentage (as a decimal) by the number. Example: 15% of $200 = 0.15 × 200 = $30. Or multiply the number by the percentage and divide by 100: 200 × 15 ÷ 100 = $30.

Percentage points measure the arithmetic difference between two percentages. If interest rates go from 3% to 5%, that is a 2 percentage-point increase, but a 66.7% relative increase. These are very different and often confused.

Sale price = Original price × (1 − discount%). Example: $80 item with 25% off = $80 × (1 − 0.25) = $80 × 0.75 = $60. Or: find 25% of $80 ($20) and subtract: $80 − $20 = $60.