Switching Unit System

If the unit system is switched during modeling, the COMSOL Multiphysics software does not convert the data in the model (except for length units and angular units in the geometry if specified). All physical constants and data in the material libraries are in SI units and defined using the unit syntax, so you can use them with any unit system because the COMSOL Multiphysics software converts these values to the corresponding values in the model’s unit system.

The units of other input data must be declared for the model using the unit syntax (or manually convert the numerical values to the new unit system).