Math & Utilities
Calculate percentages, percentage increase/decrease, and find what percentage one number is of another.
Enter your values and click Calculate to see the results.
Percentage calculations are fundamental mathematical operations used daily in finance, business, education, and personal life. A percentage represents a portion of a whole expressed as a fraction of 100. Whether you're calculating discounts, tax rates, interest rates, grade scores, or statistical data, understanding percentages helps you make informed decisions. This calculator handles all common percentage operations: finding what percentage one number is of another, calculating percentage increases or decreases, adding or subtracting percentages from values, and determining the original value before a percentage change.
Percentage calculations follow specific formulas depending on the operation. To find what percentage X is of Y, divide X by Y and multiply by 100. For percentage increase, subtract the original from the new value, divide by the original, and multiply by 100. Percentage decrease uses the same formula. When adding a percentage to a number, multiply the number by (1 + percentage/100). When finding the original value before a percentage increase, divide the final value by (1 + percentage/100). Understanding these relationships helps you verify results and apply percentage logic in various situations.
Example:
If a product costs $80 and is discounted by 25%, the discount amount is $20, making the sale price $60. If that $60 item later increases by 25%, the new price is $75, not back to the original $80 - this demonstrates that percentage changes aren't symmetrical. For another example, if you scored 85 out of 100 on a test, your score is 85%. If you later scored 42 out of 50, that's 84%, showing a slight decrease despite the smaller numbers.