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Percentage Calculator

Enter numbers to easily calculate percentages.

Percentage of a number

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% of

Percentage increase or decrease

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to

What percentage is one number of another?

is what % of

Formula verified with 40-digit decimal arithmeticHow we verify

How percentages work

A percentage is simply a part out of 100. Every percentage problem comes down to three basic questions:

What is 20% of 80?

Multiply the percent by the number, then divide by 100.

(20 × 80) ÷ 100 = 16

16 is what % of 80?

Divide the part by the total, then multiply by 100.

(16 ÷ 80) × 100 = 20%

16 is 20% of what?

Multiply the part by 100, then divide by the percent.

(16 × 100) ÷ 20 = 80

3 common mistakes to avoid

Easy traps to watch out for in school, shopping, and everyday math:

  • Points vs. percent change: If an interest rate moves from 10% to 15%, that is an increase of 5 percentage points, which equals a 50% jump in the rate itself.
  • The 50% drop trap: If an investment loses 50%, you need a 100% gain just to get back to even. A 50% gain only brings you halfway back.
  • Reversing sales tax: For a $113 total with 13% tax included, divide by 1.13 to find the $100 pre-tax price. Subtracting 13% gives $98.31, which is wrong.

Specialized percentage calculators

Pick any calculator below for step-by-step answers and quick reference tables.

Frequently asked questions

How do you calculate percentage of a number?

To find P percent of a number X, multiply P by X and then divide by 100. Formula: Result = (P × X) ÷ 100. For example, to find 15% of 80: (15 × 80) ÷ 100 = 1,200 ÷ 100 = 12.

How do you calculate what percent one number is of another?

To find what percent A is of B, divide A by B and multiply by 100. Formula: Percentage = (A ÷ B) × 100. For example, 19 out of 95 is (19 ÷ 95) × 100 = 0.20 × 100 = 20%. Note that B cannot be zero.

What is the difference between percentage change and percentage points?

Percentage change measures relative growth compared to the initial value: ((New − Old) ÷ |Old|) × 100. Percentage points is the simple difference between two percentage rates: New% − Old%. For example, an increase from 10% to 15% is a 5 percentage point increase (15 − 10 = 5 points), but a 50% relative increase ((15 − 10) ÷ 10 × 100 = 50%).

Why do standard online calculators make rounding errors?

Standard calculators use binary floating-point numbers where decimals like 0.1 cannot be represented precisely. For example, 0.5% of 201 is exactly 1.005, but rounding it with JavaScript's toFixed(2) gives 1.00 instead of the correct 1.01. PercentagesCalculators uses 40-digit arbitrary-precision decimal arithmetic to guarantee 100% exact solutions.