Free online rounding calculator. Round numbers to any number of decimal places with standard rounding, ceiling, floor, and truncation. Pure frontend math tool.
Standard rounding (round half up) rounds up when the next digit is 5 or more, and rounds down when it's 4 or less. E.g., 3.14159 β 3.14 (2 places).
Ceiling always rounds up (toward +β). Floor always rounds down (toward -β). Truncate simply cuts off extra digits without rounding.
Floating-point numbers in computers are binary approximations. The tool uses JavaScript's built-in types, so very small rounding artifacts may appear with extreme precision.
Ceiling is used for billing (round up minutes), while floor is used for age calculations (round down years). Truncate is used when you just need fewer digits.
Rounding adjusts the last digit based on the next digit. Truncating simply removes digits without any adjustment. Example: 3.14159 truncated to 2 decimals = 3.14.