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How to Calculate Percentages

How to calculate percentages step by step: discounts, sales tax, grades, and percentage increases with simple formulas and a free calculator.

What Is a Percentage?

A percentage is simply a fraction out of 100. If you score 45 out of 50 on a test, you answered 90 out of every 100 questions correctly. That is a score of 90%.

Three Formulas You Need

Finding a percentage of a number: amount = number x percentage / 100. For example, 20% of 250 is 250 x 20 / 100 = 50.

Calculating a percentage increase: divide the increase by the original and multiply by 100. A price rising from $40 to $48 is an increase of 8, so 8 / 40 x 100 = 20%.

Calculating a percentage difference: divide the difference by the larger value, then multiply by 100.

Real-Life Examples

Discounts

A jacket is $120 with a 25% discount. 25% of 120 is 30, so you pay $90. Our Percentage Calculator does this in one click, forwards or backwards.

Sales Tax

For a 7% tax on a $58 item, multiply 58 by 0.07 to get a tax of $4.06, and a total of $62.06.

Grades

Got 35 correct out of 40? 35 / 40 = 0.875, which is 87.5%. Add the percentage calculator to quizzes and projects to forecast your final grade.

Tip: Use the Calculator Backwards

Our calculator also solves reverse problems, such as: a store price is $85 after a 15% discount, so what was the original price? That is the kind of question the reverse mode answers instantly.

Frequently Asked Questions

How do I calculate a percentage increase quickly?
Subtract the old value from the new value, divide by the old value, and multiply by 100. The result is the increase percentage.
What is the difference between percent increase and difference?
Percent increase compares a change to the starting value. Percent difference compares two values to their average or the larger one, depending on the formula.
Can the Percentage Calculator handle discounts with tax?
Yes. Apply the discount percentage first, then add tax using the calculator again, or combine both mentally with the reverse mode.

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