Percentage Calculator: frequently asked questions
Straight answers to the questions people ask most about percentage math and the calculator.
How do you calculate 15% of 80?
Multiply the decimal form of the percent by the whole: 0.15 × 80 = 12. The calculator's Percent of mode does exactly this.
How is percent change calculated?
Percent change = (new value − old value) ÷ old value × 100. A positive result is an increase; a negative result is a decrease. For example, 40 to 50 is a 25% increase.
What's the difference between "what percent" and "percent of"?
Percent of finds the part given a percent and a whole (e.g., 15% of 80 = 12). What percent finds the percent given a part and a whole (e.g., 12 is 15% of 80). They reverse each other.
Do I enter percents as 15 or 0.15?
Enter 15 for 15%. The tool divides by 100 automatically, so you supply the percent value directly.
Verdict
For correct percent answers in every common scenario, the Percentage Calculator is the fastest, simplest option.