Percentage calculator: three common calculations

This tool covers the three questions people ask most often. First, what percent one number is of another, for example 25 out of 200 is 12.5%. Second, what a given percentage of a number is, such as 15% of 80 is 12. Third, how a number changes when you increase or decrease it by a percent.

Use it for discounts and sales prices, tips, tax, grades, interest and price changes. To find a sale price, enter the original price, type the discount percent and press Decrease.

Formula: part = whole × percent ÷ 100. To find the percent, use percent = part ÷ whole × 100.