Rounding Calculator
Rounding is the process of simplifying a number to a specified level of precision. This calculator supports four common rounding modes. Round to nearest finds the closest value at the desired precision, rounding 5 and above up and 4 and below down. Ceiling (round up) always moves to the next higher value. Floor (round down) always moves to the next lower value. Truncate (chop) removes digits beyond the precision without rounding. You can round to decimal places (for fractional numbers) or to the nearest ten, hundred, thousand, or higher for whole numbers. The calculator shows all four results simultaneously for comparison, helping you understand the differences between rounding methods.
Rounding methods
Round to nearest: if next digit >= 5, round up; else round down
Ceiling: always round up to next value
Floor: always round down to next value
Truncate: remove digits without rounding
Rounding examples
| Original | To nearest 0.1 | Ceiling | Floor | Truncate |
|---|---|---|---|---|
| 3.14159 | 3.1 | 3.2 | 3.1 | 3.1 |
| 2.6789 | 2.7 | 2.7 | 2.6 | 2.6 |
| 5.5 | 5.5 | 5.5 | 5.5 | 5.5 |
| 7.451 | 7.5 | 7.5 | 7.4 | 7.4 |
| -2.3 | -2.3 | -2.0 | -2.3 | -2.3 |
Rounding calculator: frequently asked questions
What does round to nearest mean?
Rounding to the nearest means finding the closest value at the desired precision. If the next digit is 5 or higher, round up. If it is 4 or lower, round down. For example, 3.45 rounds to 3.5 (nearest tenth) or 3 (nearest whole).
What is the difference between rounding, ceiling, and floor?
Rounding to nearest finds the closest value. Ceiling (rounding up) always rounds toward the next higher value. Floor (rounding down) always rounds toward the next lower value. For 3.2, ceiling is 4, floor is 3, and rounding to nearest is 3.
What is truncation?
Truncation (or chopping) removes all digits beyond a certain precision without rounding. For 3.876, truncating to 1 decimal place gives 3.8. This is different from rounding, which would give 3.9.
When should you round?
Rounding is used when you need a simpler number, when measurements have limited precision, when reporting financial values, or when a calculation result has more precision than is meaningful. Always round only at the final step of calculations to preserve accuracy.
What is banker's rounding?
Banker's rounding (also called round half to even) rounds a .5 value to the nearest even number. For example, 2.5 rounds to 2, and 3.5 rounds to 4. This reduces bias in repeated rounding operations.
Official sources
- Rounding and decimal arithmetic: NIST Special Publication 330.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.