Why a rounding tool? Numeric rounding is simply the process of approximating a number (often by removal of digits) to a simpler value that is close to the original. Different methods exist primarily to handle the “tie-breaker” situation (when a number is exactly halfway between two potential results, like 1.5).
The Multiple Methods Rounding Tool (below) uses the powerful decimal.js library to offer a wide range of standard industry rounding modes, including those that specifically address how to handle ties. As such, whether you use this tool on this webpage or download the HTML an launch locally, you will still need internet access.
The tool asks you to set the Rounding Place (where the rounding occurs) and the Rounding Mode (how the tie is broken). [For rounding with tolerance ranges, see Dual-Dimension Tolerance Rounding Tool.]
Rounding Modes Supported
The tool supports nine modes. Modes 0 through 7 are standard, deterministic methods, and Mode 8 is unique for statistical purposes.
| Mode | Name | Simple Explanation (Handling Ties) | Example (Rounding 1.5 to nearest unit) |
| 0 | Round Up | Rounds away from zero. If the number is positive, it goes up; if negative, it goes down. | 1.5 to 2.0, -1.5 to -2.0 |
| 1 | Round Down | Rounds towards zero (also called Truncate). Simply chops off the extra digits. | 1.5 to 1.0, -1.5 to -1.0 |
| 2 | Round Ceil | Rounds towards positive infinity (always up or stays the same). | 1.5 to 2.0, -1.5 to -1.0 |
| 3 | Round Floor | Rounds towards negative infinity (always down or stays the same). | 1.5 to 1.0, -1.5 to -2.0 |
| 4 | Round Half Up | Standard Commercial Rounding. Rounds to the nearest digit, and if it’s a tie (exactly half), it rounds away from zero. | 1.5 to 2.0, -1.5 to -2.0 |
| 5 | Round Half Down | Rounds to the nearest digit, and if it’s a tie (exactly half), it rounds towards zero. | 1.5 to 1.0, -1.5 to -1.0 |
| 6 | Round Half Even | Banker’s Rounding. Rounds to the nearest digit, and if it’s a tie, it rounds to the nearest even number (to reduce statistical bias). | 1.5 to 2.0, 2.5 to 2.0 |
| 7 | Round Half Ceil | Rounds to the nearest digit, and if it’s a tie, it rounds towards positive infinity. | 1.5 to 2.0, -1.5 to -1.0 |
| 8 | Stochastic | Zero-Bias Rounding. It randomly rounds up or down, weighted by the fractional part, to ensure the average of many roundings is statistically correct. | 1.5 to 2.0 (50% of the time), 1.5 to 1.0 (50% of the time) |