Supporting reference
Quick reference
Short references for people who want to check the math after using the calculator.
Common examples
10% of 50010 / 100 x 500 = 50
25% discount on $8080 - 20 = $60
Increase from 120 to 15030 / 120 x 100 = 25%
30 is what percent of 200?30 / 200 x 100 = 15%
Add 8% tax to $49.9949.99 + 4.00 = $53.99
Percentage formulas
Percent of a number(Percent / 100) x Number
Part as percent of whole(Part / Whole) x 100
Increase or decrease((New - Old) / Old) x 100
Add percentageNumber + (Number x Percent / 100)
Subtract percentageNumber - (Number x Percent / 100)
Percentage difference|A - B| / ((|A| + |B|) / 2) x 100
DiscountOriginal Price - (Original Price x Discount / 100)
Tax or VATPrice x (1 + Tax Rate / 100)
FAQ
Percentage calculator questions
How do I calculate a percentage?
Divide the part by the whole, then multiply by 100. For example, 30 out of 150 is 20%.
How do I calculate percentage increase?
Use ((new value - old value) / old value) x 100.
How do I calculate percentage decrease?
Use the same change formula and read a negative result as a decrease, or calculate ((old value - new value) / old value) x 100.
How do I calculate a discount percentage?
Multiply the original price by the discount rate divided by 100, then subtract that amount from the original price.
Is this percentage calculator free?
Yes. PercentSwift is free to use and does not require an account.
Does the calculator work on mobile?
Yes. The calculator is fully responsive and works on phones, tablets, laptops, and large desktop screens.
Percentage guide Learn more about percentage calculations
A percentage is a number expressed as a part of 100. Percentages make it easier to compare values, explain changes, calculate prices, estimate tips, understand taxes, and measure progress.
To calculate a basic percentage, divide the part by the whole and multiply by 100. To find a percent of a number, divide the percent by 100 and multiply by the number.
Percentage increase and percentage decrease compare an old value with a new value. A discount calculator subtracts a percent from the original price. A tax or VAT calculator adds or removes a tax rate. A tip calculator adds a gratuity to a bill.