Rounding Calculator
Round a number to decimal places, significant figures or the nearest multiple, with a choice of rounding rule.
About the Rounding Calculator
School rounding looks at the next digit: 5 or more rounds up, less rounds down. Banker's rounding sends exact halves to the nearest even digit (2.5 → 2, 3.5 → 4), which avoids a bias when rounding many numbers, and is used in finance and statistics.
Significant figures count from the first non-zero digit: 0.004567 to 2 significant figures is 0.0046.
The formula
Round half up: look at the next digit; 0–4 down, 5–9 up
How each rule treats halves
| Number | Half up | Half even | Ceiling | Floor |
|---|---|---|---|---|
| 2.5 | 3 | 2 | 3 | 2 |
| 3.5 | 4 | 4 | 4 | 3 |
| -2.5 | -3 | -2 | -2 | -3 |
| 2.4 | 2 | 2 | 3 | 2 |
| -2.6 | -3 | -3 | -2 | -3 |
Worked example
Example: Rounded to 3 decimal places = 3.142
- Inputs: Number: 3.14159; Round to: Decimal places; How many / multiple: 3; Halves (…5) go: Away from zero (school rounding).
- Formula: Round half up: look at the next digit; 0–4 down, 5–9 up
- Result: Rounded to 3 decimal places = 3.142
Questions people ask
Why does Excel give a different answer sometimes?
Spreadsheets store numbers in binary, so 2.675 may really be 2.67499…; this calculator works in exact decimal.
What is rounding to the nearest 5?
Choose “Nearest multiple of” and enter 5: 23 → 25, 22 → 20.