# BHoM Unit conventions

This page describes the Units conventions for the BHoM.

## General philosophy: use SI!

The BHoM framework adheres as much as possible to the conventions of the SI system.

Any Engine method must operate in SI to avoid complexity of Unit Conversions inside calculations. Conversion to and from SI is the responsibility of the Converts inside the Adapters.

When some units (derived or not) are not explicitly covered by this Wiki page, it is generally safe to assume that measures expressed in SI units will not be converted by the BHoM.

• Mass: kilograms [kg]
• Length: meters [m]
• Force: Newtons [N]
• Moments: [N*m]
• Stress/Pressure: [N/m²]
• Spring constraints: [N/m]
• Rotational constraints: [N*m/rad]
• Temperature: [K]

## Localisation toolkit

The Localisation_Toolkit provides support for conversion between SI and other units systems.

## Quantity attributes

BHoM object properties can be decorated with a Quantity Attribute to define (in SI) what unity the property should be considered in. This is to be applied only to properties that are of a primitive numerical type, e.g. int, double, etc.

See Quantities_oM for the available attributes.

Last update: March 17, 2023