Percentages are one of the most frequently used mathematical concepts in daily life. When you see a "30% off" sale sign, your brain needs to convert that into an actual dollar amount to know if the deal is worthwhile. When your bank offers a 4.5% interest rate, you need to calculate what that means for your savings over a year. Percentages appear in nutrition labels, exam scores, tax rates, investment returns, and weather forecasts.
The word "percent" literally means "per hundred." So 25% means 25 out of every 100. This makes percentages a standardized way to compare values of different sizes. Whether you are comparing test scores across different exams with different totals, or comparing growth rates of companies with different revenues, percentages put everything on the same scale.
One common source of confusion is the difference between percentage change and percentage point change. If a tax rate goes from 5% to 8%, the percentage point change is 3 (simply 8 minus 5). But the percentage change is 60%, because 3 is 60% of the original 5%. Financial news often mixes these up, so understanding the distinction helps you interpret reports more accurately.
Divide the percentage by 100 and multiply by the number. For example, 20% of 150 = (20/100) × 150 = 30. This formula works for any percentage and any number. Our calculator does this instantly — just enter the percentage and the number to see the result.
Percentage change measures how much a value has increased or decreased relative to the original. The formula is: ((New - Old) / Old) × 100. A positive result means an increase, while a negative result means a decrease. This is commonly used to track price changes, salary raises, and investment returns.
A percentage point is an absolute difference between two percentages, while a percentage describes a relative change. For example, if interest rates rise from 3% to 5%, that is a 2 percentage point increase but a 66.7% relative increase. This distinction matters in finance, economics, and statistics.
To find what percentage one number is of another, divide the part by the whole and multiply by 100. For example, if you scored 45 out of 60 on a test, that is (45/60) × 100 = 75%. Use the second calculator on this page to get this result instantly.
Yes. To calculate sales tax, enter the tax rate as the percentage and the item price as the number. For discounts, do the same with the discount rate. The result tells you the tax or discount amount. Subtract it from the original price for the final cost after discount, or add it for the total with tax.