Percentage Calculator
Solve common percentage questions, including percent of a value, percent change, percentage increase, and percentage decrease.
Formulas
Percent of value = value × percent / 100 Percent change = (new value - old value) / old value × 100
Examples
15% of 240 is 36. A change from 80 to 100 is a 25% increase. A change from 100 to 80 is a 20% decrease.
Common uses
- Discounts, sales tax, tips, fees, and price comparisons.
- Score changes, growth rates, grade percentages, and survey results.
- Budget changes, rent increases, investment movement, and business metrics.
FAQ
Why is a 20% decrease not reversed by a 20% increase?
Because the second percentage is applied to a smaller base. Dropping from 100 to 80 and then increasing 20% gives 96.
Can percentages be negative?
Yes. A negative percent can represent a decrease, loss, refund, or reverse adjustment depending on context.
What if the start value is zero?
Percent change from zero is undefined in ordinary percentage math, because division by zero is not meaningful.