Rounding Calculator
Round any number to a number of decimal places, significant figures, or the nearest multiple — using standard, banker’s, ceiling, floor or truncation rules.
Result
Enter your values and select Calculate to see the result.
How to use this calculator
- Enter the number and choose what to round to.
- For decimal places, negative values round to the left of the decimal point: −1 rounds to tens, −2 to hundreds.
- Choose a rounding rule. “Half away from zero” is what most people learn at school.
Formula
The number is scaled so the target digit is in the units place, rounded with the chosen rule, then scaled back.
- Half away from zero: 2.5 → 3, −2.5 → −3
- Half to even (banker’s): ties go to the even digit, 2.5 → 2, 3.5 → 4, which avoids bias when rounding many values
- Up (ceiling) and down (floor): always toward +∞ or −∞
- Truncate: drop the extra digits, moving toward zero
For significant figures, the number of decimal places is sig figs − 1 − floor(log₁₀|x|).
Worked example
2.345 to 2 decimal places
Standard rounding gives 2.35. Banker’s rounding gives 2.34, because 4 is the even neighbour.
0.0012345 to 3 significant figures
The first significant digit is in the thousandths place, so keep 1, 2, 3: 0.00123.
Assumptions and limitations
- Values are corrected for binary floating-point artefacts before rounding, so 2.345 rounds as written rather than as 2.34499999….
- Up to 15 decimal places or significant figures are supported.
Frequently asked questions
Why does Excel sometimes round differently?
Spreadsheet ROUND uses half away from zero, but binary storage can make a value such as 2.675 slightly smaller than it looks. This calculator corrects for that tiny error first.
When is banker’s rounding used?
In finance and statistics, and as the default in several programming languages, because rounding ties to even avoids an upward bias over many values.