In Metafor, as in most FE codes, units are not explicitly defined. The user must enter input data in a consistent way.
| SI | SI (mm) | |
|---|---|---|
| Length | $\mbox{m}$ | $\mbox{mm}$ |
| Force | $\mbox{N}$ | $\mbox{N}$ |
| Mass | $\mbox{kg}$ | $\mbox{tonne}$ |
| Time | $\mbox{s}$ | $\mbox{s}$ |
| Stress | $\mbox{Pa } \left ( \mbox{N}/\mbox{m}^2 \right ) $ | $\mbox{MPa } \left ( \mbox{N}/\mbox{mm}^2 \right ) $ |
| Energy | $\mbox{J}$ | $\mbox{mJ } \left ( 10^{–3} \mbox{J} \right ) $ |
| Density | $\mbox{kg/m³}$ | $\mbox{tonne} / \mbox{mm}^3$ |
For example, if the geometry (point coordinates) is expressed in meters and the boundary conditions (loads) in Newton, the Young's Modulus appearing in the material definition must be expressed in $\mbox{N/m}^2$. Likewise, a geometry in meters and a Young's Modulus in $\mbox{kg/m}^2$ lead to forces in $\mbox{kg}$.