Work out everyday percentage questions in one place—find a percent of a number, reverse a percentage, or measure how much a value went up or down.
Select the type of problem, then enter the two values described by your chosen mode.
How to use Percentage Calculator, plus the formulas and logic behind the results.
The Percentage Calculator solves common percent problems: finding a percent of a number, reversing a percentage, increasing or decreasing a value by a percent, and measuring percent change between two numbers.
Percent of a number: (X ÷ 100) × YWhat percent: (X ÷ Y) × 100Increase: Y × (1 + X ÷ 100)Decrease: Y × (1 − X ÷ 100)Percent change: ((Y − X) ÷ |X|) × 100Quick percentage formulas
The calculator applies the selected mode formula directly to the two inputs. Division by zero is blocked for “what percent” and percent-change modes. Results are rounded for readable display.
Results are mathematical estimates. Rounding may differ slightly from manual calculations.
Common questions about this calculator and how to use the results.
A percentage calculator is an online tool that helps calculate percentages, percentage changes, increases, decreases, discounts, and other percentage-related problems. It can save time compared with calculating percentages manually.
To calculate a percentage, divide the part by the whole and multiply the result by 100. For example, 25 out of 100 is 25%, while 20 out of 80 is 25%.
Divide the first number by the second number and multiply by 100. For example, 30 is what percentage of 120? The calculation is 30 ÷ 120 × 100 = 25%.
Subtract the original value from the new value, divide the difference by the original value, and multiply by 100. The formula is: Percentage Increase = (New Value − Original Value) ÷ Original Value × 100.
Subtract the new value from the original value, divide the difference by the original value, and multiply by 100. This determines how much the value has decreased relative to the original amount.
Subtract the two values, take the absolute difference, divide it by the average of the two values, and multiply by 100. This method is useful when neither value is considered the original.
Percentage change measures how much a value has changed relative to its original value. Use the formula: (New Value − Original Value) ÷ Original Value × 100.
Divide the numerator by the denominator and multiply the result by 100. For example, 1/4 = 0.25, and 0.25 × 100 = 25%.
Multiply the decimal by 100 and add the percent symbol. For example, 0.35 × 100 = 35%, so 0.35 is equal to 35%.
Convert the percentage to a decimal and multiply it by the number. For example, 20% of 150 is 0.20 × 150 = 30.
Subtract the sale price from the original price, divide the difference by the original price, and multiply by 100. For example, if a $100 item is reduced to $80, the discount is 20%.
Divide the sale price by 1 minus the discount rate expressed as a decimal. For example, if an item costs $80 after a 20% discount, the original price is $80 ÷ 0.80 = $100.
Multiply the pre-tax amount by the tax rate expressed as a decimal. For example, a 10% tax on $200 is $200 × 0.10 = $20, making the total $220.
Percentage increase compares a new value with an original value and shows how much the value increased. Percentage difference compares two values without treating either one as the original.
A percentage calculator can be used for discounts, sales tax, tips, interest, grades, price changes, business calculations, financial planning, and many other everyday calculations.