Rounding keeps numbers readable and honest about their precision. Different fields use different rules: shops round half up, banks and statisticians often round half to even to avoid bias, and engineers round to significant figures.
How to use the Rounding Calculator
- Number
- Round to
- Decimal places
- Nearest fraction
- Significant figures
- Rounding mode
Everything is calculated in your browser, so results appear instantly and nothing you type is sent to a server.
How it works
Choose what to round to and the rounding mode. Directed modes (up, down, ceiling, floor) always go one way; “half” modes round to the nearest value and only differ when the number is exactly halfway.
Formula
Half up: round to the nearest; ties go away from zero
Half to even: ties go to the even neighbour
Worked example
Inputs: Number: 2.675; Round to: Decimal places; Decimal places: 2; Rounding mode: Half up.
Results: Result = 2.68; How it was rounded = Rounded to 2 decimal place(s), mode: half up; Rounding error (result − number) = 0.005.
Key terms
- Rounding mode
- The rule for choosing between two neighbouring values.
Frequently asked questions
What is half up rounding?
Round to the nearest; exact halves go away from zero: 2.5 → 3, −2.5 → −3.
What is banker's rounding?
Half to even: 2.5 → 2 and 3.5 → 4, which avoids a systematic upward bias.
What does negative decimal places mean?
Rounding to tens (−1), hundreds (−2) and so on.
How do I round to the nearest 1/8 inch?
Choose "Fractions" and 1/8.