How to Calculate Percentages
Percentage calculation is one of the most common mathematical operations in everyday life: from store discounts to sales tax, from stock market changes to interest rates. This calculator handles the four main percentage operations.
Percentage Formulas
Percentage of a number (X% of Y): Result = Y x X / 100
Percentage change between two values: Change = ((Y - X) / |X|) x 100
Adding a percentage: Result = Y x (1 + X / 100)
Subtracting a percentage (discount): Result = Y x (1 - X / 100)
How It Works
Select the type of calculation you need, enter the two values, and get the instant result with the detailed formula. The calculator handles decimal numbers and negative values.
When to Use This Calculator
Percentages are everywhere in daily life:
- Shopping: calculating discounts on products ("30% off $89")
- Finance: calculating sales tax, income tax, interest rates
- Work: revenue changes, salary increases
- School: grades, statistics, proportions
- Cooking: adjusting recipe quantities
Practical Examples
If a product costs $120 and has a 25% discount, the sale price is 120 x (1 - 0.25) = $90. If your salary goes from $3,000 to $3,300, the percentage increase is ((3,300 - 3,000) / 3,000) x 100 = 10%.
Percentage calculation forms the basis of more complex financial operations such as tax calculations, compound interest, and investment returns.