Formulas used
X% of Y = (X ÷ 100) × Y. Percentage = (part ÷ whole) × 100. % change = ((final − initial) ÷ initial) × 100.
Percentage calculator
Choose a calculation mode and fill in the fields. The result appears instantly.
Quick examples
10% of 250 = 25. 30 is 15% of 200. From $80 to $100 = 25% increase. From $120 to $90 = 25% decrease.
When to use this calculator
Useful for calculating discounts while shopping, salary raises, investment returns, tax rates, and grade averages. Also great for tracking stock or crypto price changes — for example, a stock moving from $50 to $65 represents a 30% gain. Works for any scenario involving percentage calculations.
Frequently asked questions
How do I find X% of a number?
Multiply the number by the percentage and divide by 100. For example: 15% of 200 = (15 × 200) ÷ 100 = 30.
How do I find what percentage one number is of another?
Divide the part by the whole and multiply by 100. For example: 30 ÷ 200 × 100 = 15%.
How do I calculate percentage change?
Subtract the initial value from the final, divide by the initial, and multiply by 100. From 80 to 100: (100 − 80) ÷ 80 × 100 = 25%.
How do I calculate a discount?
Find X% of the original price and subtract it. Formula: final price = original × (1 − discount ÷ 100). Example: 20% off $150 = $120.
What is the difference between percentage increase and decrease?
An increase means the final value is higher than the initial (positive change). A decrease means it is lower (negative change). The same formula applies to both.
How do I calculate a percentage raise in salary?
Divide the new salary by the old one, subtract 1, and multiply by 100. From $3,000 to $3,300: (3300 ÷ 3000 − 1) × 100 = 10%.