What is "round half up"?

When the digit immediately after the rounding position is exactly 5, the result is rounded away from zero. So 2.5 becomes 3 and −2.5 becomes −2. This is the most common rule taught in schools.

What is banker's rounding (round half to even)?

When the digit after the rounding position is exactly 5 with no further non-zero digits, the result is rounded to the nearest even number. So 2.5 rounds to 2 and 3.5 rounds to 4. This minimizes accumulated rounding error over many values and is the default in Python 3 and IEEE 754.

Truncation simply drops all digits beyond the chosen decimal place without looking at the next digit. 2.9 truncated to 0 places is 2, not 3. It always rounds toward zero.

Why do different programming languages round differently?

Many modern languages (Python 3, Java's BigDecimal, IEEE 754) default to round half to even to avoid statistical bias. Older conventions (Excel, JavaScript's Math.round) use round half up or round half away from zero.

Does this tool handle negative numbers?

Yes. For round half up the tie-breaking rule is "away from zero," so −2.5 rounds to −3 under some conventions and −2 under others. This tool applies the most common school definition: negative ties round toward zero (−2.5 → −2).

Rounding Rules Helper

Name: Rounding Rules Helper
Availability: InStock
Author: Nham Vu

Enter a number and decimal places to see the rounded result plus a plain-English explanation of which rounding rule applied.

Enter a Number

Number

Decimal places

Rounding method

Round half up Ties round away from zero (common school rule)

Round half down Ties round toward zero

Round half to even Banker's rounding — ties go to nearest even digit

Truncate Drop extra digits, always toward zero

Enter a number on the left and click Round It to see the result.

Original

Rounded

Step-by-step explanation

All methods compared

Method	Result

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Summary