# Factor of safety

## Description

Factor of safety (FoS) or (FS), is a term describing the structural capacity of a system beyond the expected loads or actual loads. Essentially, how much stronger the system is than it usually needs to be for an intended load. A Factor of safety is a design criteria that an engineered component or structure must achieve. The ultimate strength is the maximum stress that a material can withstand before it breaks or weakens. The Factor of safety is the ratio of the applied stress to the ultimate stress.

Related formulas## Variables

FS | Factory of safe (dimensionless) |

UTS | The ultimate stress (Pa) |

R | The applied stress (Pa) |