Precision

Precision of Conversions and Representations

Units.NET was not designed for high-precision, but rather a tool of convenience and simplicity. As a result, there is usually a small error involved in both representing a value of a unit and converting between units. We are open to ideas how to improve this, while still keeping it simple and convenient.

• A base unit is chosen for all quantities
  • SI base unit is preferred where available, such as LengthUnit.Meter and VolumeUnit.CubicMeter.
  • MassUnit.Gram was chosen to better support SI prefixes like kilo, mega etc.
• The value is typically represented by a double value (64-bit)
  • A few quantities use decimal due to having both very large and very small units: Power, Information and BitRate.
• Conversions go via the base unit.
  • Centimeter => Meter => Kilometer
  • As a result, most conversions has a rounding error. The error is larger for units that are way larger or way smaller than the base unit.
  • A rounding error of 1e-5 is accepted for round-trip conversion of most units in the library. In many use cases this is sufficient, but for others this may not be acceptable.
  • There is support for custom conversion functions between unit A to unit B, typically to add 3rd party units. This can also be used to improve the precision for specific conversions since it no longer converts via the base unit.