Calculation Policy

The Standard Calculator follows the order of operations

The Standard Calculator on the home page supports addition, subtraction, multiplication, division, and parentheses. Multiplication and division come before addition and subtraction: 2 + 3 × 4 = 14, while (2 + 3) × 4 = 20.

% divides the value immediately before it by 100. For example, 200 × 10% = 20 and 200 + 10% = 200.1. To increase 200 by 10%, enter 200 × (1 + 10%).

Standard Calculator results are rounded to a maximum of 10 decimal places, with unnecessary trailing zeros removed. The “≈” symbol appears when rounding for display changes the value. The default of 2 decimal places and the precision choices described below apply to the Percentage Calculator.

Expressions can contain up to 256 characters. Each number can have up to 15 digits before the decimal point and 10 after it. .5 is treated as 0.5. Commas, scientific notation, and functions are not supported. Multiplication must be explicit: enter 2 × (3 + 4) instead of 2(3 + 4). The absolute value of every intermediate value and result must be no greater than 10⁵⁰.

Recent calculations are kept only on the current page and disappear when you refresh it. Your expressions and results are not sent to a server.

Both calculators use decimal arithmetic

The Standard Calculator and Percentage Calculator share a decimal.js engine that processes inputs as decimal strings and uses 60 significant digits for internal calculations. This avoids carrying the binary floating-point representation errors of JavaScript’s default number type, such as those seen in 0.1 + 0.2, into ordinary decimal calculations.

However, a finite number of digits cannot exactly represent a repeating decimal such as 1 ÷ 3. Internal calculation precision and the number of decimal places displayed on screen are different settings.

Choose decimal places in the Percentage Calculator

Results display 2 decimal places by default. You can choose 0, 2, 4, 6, or 10 decimal places. Trailing zeros are retained to match your choice. Commas separate thousands, and a period marks the decimal point.

Values are rounded to the nearest value at the selected precision. Exact ties are rounded away from zero, for both positive and negative numbers. A negative value that rounds to zero is displayed without a minus sign.

The “≈” symbol appears when rounding for display changes the value. Its absence means no additional rounding was needed for display; it does not guarantee infinite precision for every mathematical calculation.

Percentage Calculator input limits

Each input can have up to 15 digits before the decimal point and 10 after it. Positive and negative numbers are accepted, as are correctly placed thousands separators. Unit symbols, expressions, and scientific notation are not accepted.

• Accepted examples: 1234.5, 1,234.5, -25
• Not accepted: 12,34, 15%, 1+2, 1e3
• Use the same unit for both values in “What percent?” and “Percentage change”. In “Percentage of a number”, the second input is a percentage (%). Units are not converted automatically.

Invalid calculations show an explanation

Empty inputs and invalid number formats show an error message instead of a result. Division by zero also shows an error, rather than displaying infinity or treating it as a valid numerical result.

• In “What percent?”, the whole cannot be zero.
• In “Percentage change”, the original value must be greater than zero. An original value of zero or less is outside the scope of this calculator.
• Changing an input or calculation mode clears the previous result. Calculate again to get a result for the new inputs.

Each calculator explains its formula

Calculation methods vary by purpose and subject. No single display precision or rounding rule applies to every web calculator, so we explain our choices and provide the formulas, conditions, and examples for each calculator.

The Percentage Calculator calculates general mathematical ratios. Tasks with their own rules, such as tax calculations or invoicing, may produce different results because of specific requirements for truncation, rounding, or the order of calculations.