How to calculate percentages?
A percentage is a way of expressing a number as a fraction of 100. It is widely used in finance, shopping, statistics, science, and everyday life.
Common percentage formulas
- Increase : New = Original × (1 + %/100)
- Decrease : New = Original × (1 − %/100)
- % of a number : Result = Number × %/100
- % difference : % = |V1 − V2| / Average × 100
- % change : % = (New − Old) / Old × 100
- Reverse % (increase) : Original = Final / (1 + %/100)
- Reverse % (decrease) : Original = Final / (1 − %/100)
Real-world examples
- Sales & Discounts : A $80 item with 25% off costs $60. You save $20.
- Salary raise : A $3,000 salary with a 5% raise becomes $3,150.
- Tax : A $100 product with 20% tax costs $120 total.
- Tips : A $50 bill with 15% tip = $7.50 tip, $57.50 total.
- Inflation : Prices rising from $100 to $110 is a 10% increase.