Percentage calculator
Type your question, get the answer. Calculate percentages of a number, find what percent one number is of another, or compute increases and decreases.
About the percentage calculator
Percentages are everywhere — tips at a restaurant, discounts in a store, grades on an exam, a raise at work, inflation in the news. This calculator handles all of those cases from a single interface. Instead of choosing a mode from a menu, you type your question as a sentence and the tool reshapes itself to answer it. It handles six different question types: finding a percentage of a number, finding what percent one number is of another, working backwards from a percentage to the original, and calculating increases, decreases, and percent changes between two values.
Six ways to calculate a percentage
Every percentage problem boils down to one of these six question shapes. Pick the one that matches what you're trying to solve.
What is X% of Y?
Find a percentage of a number. Example: what is 15% of 80? Answer: 12. Formula: (X ÷ 100) × Y. Use this for tips, taxes, discounts, and any time you need to take a fraction of a total.
X is what % of Y?
Find what percent one number is of another. Example: 45 is what percent of 180? Answer: 25%. Formula: (X ÷ Y) × 100. Use this for grades, completion rates, and proportions.
X is Y% of what?
Find the original number when you know a percentage of it. Example: 30 is 25% of what? Answer: 120. Formula: X ÷ (Y ÷ 100). Use this when a sale price is given and you want the original.
X increased by Y%
Add a percentage to a number. Example: 100 increased by 25% is 125. Useful for markups, raises, and inflation adjustments. Formula: X × (1 + Y ÷ 100).
X decreased by Y%
Subtract a percentage from a number. Example: 100 decreased by 25% is 75. Useful for discounts, sale prices, and depreciation. Formula: X × (1 − Y ÷ 100).
Percent change from X to Y
Calculate the increase or decrease between two values as a percentage. Example: from 80 to 100 is a 25% increase. Formula: ((Y − X) ÷ X) × 100. Use this for comparing prices, salaries, or any before-and-after values.
How to think about percentages
A percentage is a fraction with 100 as the denominator. "25%" means 25 out of 100, or 0.25. All six question shapes on this page are variations of the same underlying math: multiplying or dividing by 100 in different combinations. "What is 15% of 80" is 15/100 × 80. "45 is what % of 180" is 45/180 × 100. Once you see that every percentage problem is a proportion — part, whole, and rate — the six shapes become interchangeable views of the same relationship.