Percentage Calculator
Three ways to calculate percentages — pick the question that matches yours.
How to Calculate Percentages
Percentages are one of the most frequently used calculations in everyday life — from calculating discounts and sales tax to understanding test scores, interest rates, and business growth. Our free percentage calculator covers the three most common percentage problems in one clean interface, so you never have to remember which formula to use.
Finding a Percentage of a Number
The most common percentage question is "what is X% of Y?" To solve it manually, divide the percentage by 100 then multiply by the number. For example, to find 15% of $80: (15 ÷ 100) × 80 = $12. This calculation is essential for working out tips, discounts, taxes, and commissions.
Finding What Percentage One Number Is of Another
To find what percentage 45 is of 180, divide the part by the whole and multiply by 100: (45 ÷ 180) × 100 = 25%. Use this when tracking progress toward a goal, evaluating exam scores, or analyzing what share of a total something represents.
Finding the Whole When You Know the Part and Rate
If you know a value represents a certain percentage of a larger number and need to find that larger number, divide the part by the percentage and multiply by 100. If $45 is 30% of some total, the full amount is (45 ÷ 30) × 100 = $150. This is useful for reverse-engineering totals from partial figures — helpful in budgeting and tax calculations.
Frequently Asked Questions
What is the formula for calculating a percentage?
The basic percentage formula is: Percentage = (Part ÷ Whole) × 100. For example, if you scored 45 out of 60 on a test, your percentage is (45 ÷ 60) × 100 = 75%. To find a percentage of a number, multiply the number by the percentage and divide by 100.
How do I calculate X% of a number?
To find X% of a number Y, use the formula: Result = (X ÷ 100) × Y. For example, 20% of 150 = (20 ÷ 100) × 150 = 0.20 × 150 = 30. The first section of our calculator handles this instantly.
What is 20% of 100?
20% of 100 is 20. Calculated as (20 ÷ 100) × 100 = 20. Other common ones: 10% of 100 = 10, 25% of 100 = 25, 50% of 100 = 50, 75% of 100 = 75.
How do I find what percentage one number is of another?
To find what percentage A is of B: (A ÷ B) × 100. For example, 30 as a percentage of 150 = (30 ÷ 150) × 100 = 20%. This is useful for calculating test scores, sale discounts, and progress toward targets.
What is the difference between percent and percentage point?
A percent (%) expresses a ratio as a fraction of 100. A percentage point is the absolute arithmetic difference between two percentages. If interest rates rise from 3% to 5%, that is a 2 percentage point increase — but a 66.7% relative increase in the rate itself. The two terms are frequently confused in news and finance.