Factor of safety
FACTOR BY WHICH AN ENGINEERED SYSTEM'S CAPACITY IS INCREASED OVER THE EXPECTED REQUIREMENT TO ENSURE SAFETY IN THE FACE OF ERROR OR UNCERTAINTY
Safety factor; Overbuilt; Design margin; Factor and Margin of Safety; Margin of safety (engineering)
In engineering, a factor of safety (FoS), also known as (and used interchangeably with) safety factor (SF), expresses how much stronger a system is than it needs to be for an intended load. Safety factors are often calculated using detailed analysis because comprehensive testing is impractical on many projects, such as bridges and buildings, but the structure's ability to carry a load must be determined to a reasonable accuracy.