Percentage Calculator
Free percentage calculator for all percent problems: find X percent of Y, what percent X is of Y, and percent increase or decrease between two numbers.
About this tool
Percentages show up everywhere: sale discounts, tips, grades, interest rates, and statistics. The math is simple, but it is easy to mix up which number goes where - and a small mistake can cost real money.
This percentage calculator handles the three most common percent problems. Pick the type of question you have, enter your two numbers, and get an instant, exact answer.
How to use
First choose the mode that matches your question: 'X is what % of Y' (for example, 45 is what percent of 180), 'X% of Y' (for example, 20% of 250), or percent increase/decrease between two numbers.
Enter X and Y, then press Calculate Percentage. The answer appears right away, formatted to two decimal places, so you can use it directly in your own math.
The math behind it
The three modes use three formulas. 'X is what percent of Y' divides X by Y and multiplies by 100. 'X percent of Y' multiplies Y by X/100. Percent change subtracts the old value from the new value, divides by the old value, and multiplies by 100 - a positive result is an increase, a negative one a decrease.
For example, going from 80 to 100 is (100-80)/80 x 100 = 25% increase.