Rounding without surprises
Rounding replaces a number with a simpler, nearby one. You can round to a number of decimal places, to a number of significant figures, or to the nearest multiple such as 5, 10, 0.05 or 250.
Different fields use different rules for a tie like 2.5: standard half-up gives 3, while banker's rounding (half to even) gives 2 to avoid a systematic upward bias. This calculator supports seven rules and works on the exact digits you typed, so 1.005 correctly rounds to 1.01.
How it is calculated
Worked example
1234.5678
- 2 decimal places
- 1234.57
- 3 significant figures
- 1230
- Nearest 10
- 1230
- Whole number
- 1235
Rounding rules compared for 2.5 and −2.5
| Rule | 2.5 | −2.5 |
|---|---|---|
| Half up | 3 | −2 |
| Half to even | 2 | −2 |
| Ceiling | 3 | −2 |
| Floor | 2 | −3 |
| Truncate | 2 | −2 |
| Away from zero | 3 | −3 |
Why rounding rules matter in practice
Banker's rounding (round half to even) is used in accounting and statistics because always rounding 0.5 up biases a long series of roundings slightly higher on average; rounding half-to-even cancels that bias out over many numbers, which is why some financial systems prefer it to the always-round-up rule taught in school.