How to Use the Percentage Calculator
Percentages are everywhere — discounts at the store, exam scores, tax rates, tips at restaurants, and investment returns. Our free online Percentage Calculator solves the three most common percentage problems instantly, saving you time and mental math.
- What is X% of Y? Enter a percentage and a number to find the result. For example, "What is 15% of 200?" → Answer: 30. This is perfect for calculating discounts, tips, and tax amounts.
- X is what % of Y? Enter two numbers to find what percentage the first is of the second. For example, "30 is what percent of 200?" → Answer: 15%. Great for exam scores and performance metrics.
- Percentage Change: Enter an old value and a new value to calculate the increase or decrease. For example, "From 100 to 120" → Answer: +20% increase. Ideal for tracking price changes, growth rates, and investment returns.
Percentage Formulas Explained
Understanding the math behind percentages can be helpful for everyday situations:
- Finding X% of Y: Multiply Y by X, then divide by 100. Formula:
Result = Y × (X / 100) - Finding what % X is of Y: Divide X by Y, then multiply by 100. Formula:
Percentage = (X / Y) × 100 - Percentage Change: Subtract the old value from the new value, divide by the absolute old value, and multiply by 100. Formula:
Change = ((New - Old) / |Old|) × 100
Need more calculators? Check out our Discount Calculator, Tip Calculator, or EMI Calculator.
Frequently Asked Questions
How do I calculate the percentage of a number?
To find X% of Y, multiply Y by X and divide by 100. For example, 15% of 200 = 200 × 15 ÷ 100 = 30. Our calculator does this instantly — just enter the values and click Calculate.
How do I find what percentage one number is of another?
Divide the part by the whole and multiply by 100. For example, 30 is what percent of 200? Answer: (30 ÷ 200) × 100 = 15%.
What is percentage change?
Percentage change measures how much a value has increased or decreased relative to the original. A positive result means an increase; negative means a decrease. For example, going from 100 to 120 is a +20% increase.
How do I calculate a discount?
Use the first calculator: enter the discount percentage and the original price. For example, "What is 25% of $80?" gives you $20 — so the discounted price is $80 - $20 = $60. Or use our dedicated Discount Calculator.