Percentage Calculator
Three-in-one: find any percentage, work out X% of Y, or calculate the original number.
About the Percentage Calculator
Percentages are everywhere — from store discounts and exam scores to tax rates and investment returns. Yet many people still reach for a calculator every time they need one. This free Percentage Calculator handles the three most common questions in one place.
What Is a Percentage?
A percentage is a fraction expressed out of 100. The word itself comes from the Latin per centum, meaning "by the hundred." When you say a shirt is 30% off, you mean 30 parts out of every 100 are subtracted from the price. When a class scores an average of 78%, that means 78 correct answers per 100 possible.
Three Common Calculations
1. What is X% of Y? — Multiply Y by (X/100). If you want to know what 20% of 200 is: 200 × 0.20 = 40. Use this for tips, discounts, or commission amounts.
2. X is what percent of Y? — Divide X by Y and multiply by 100. If 45 out of 200 students passed a test, that is (45/200) × 100 = 22.5%. Use this to express a part as a share of the whole.
3. Percentage change — Subtract the old value from the new value, divide by the old value, and multiply by 100. If sales rose from 800 to 960, the increase is (160/800) × 100 = 20%.
Real-World Uses
Shopping: Calculate final price after a coupon or sale. A $120 jacket at 25% off saves you $30, bringing the price to $90.
Grades: Turn raw scores into percentages. Scored 47 out of 60? That's 78.3%.
Finance: Calculate income tax brackets, interest charges, or portfolio allocation percentages.
Nutrition: Find out what percentage of daily calories come from fat or protein.
Business: Evaluate profit margins, growth rates, or market share changes quarter-over-quarter.
Tips for Accuracy
Always confirm which value is the "base" (the starting or whole number) to avoid dividing by the wrong figure. When computing tip percentages at a restaurant, remember that the base is the pre-tax subtotal, not the total bill. For investment returns, use the original investment as the base, not the current value.
This tool computes all three variants simultaneously so you can cross-check your work quickly without switching between formulas.