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.

This is a design decision and I am open to improvements, but basically it goes something like this:

• A base unit is chosen for all classes of units, which is represented by a double value (64-bit).
• As an example, for length, area and volume these are meters, m² and m³ respectively. I have typically chosen the base SI units where possible.
• A design decision was made to let all conversions go via the base unit, because that simplified the implementation a great deal.
• As a result, any conversion and even round-trip conversions (to a different unit and back) do come with an error, and the error is larger for units that are way larger or way smaller than the base unit.
• In the unit tests I accept an error less than 1E-5 for all units I've added so far. In many usecases this is sufficient, but for some usecases this is either not acceptable or something you just need to be aware of.