factor of safety

American  

noun

1. the ratio of the maximum stress that a structural part or other piece of material can withstand to the maximum stress estimated for it in the use for which it is designed.

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factor of safety British  

noun

1. Also called: safety factor.  the ratio of the breaking stress of a material or structure to the calculated maximum stress when in use

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Etymology

Origin of factor of safety

First recorded in 1855–60

Example Sentences

“Metro added a 20% factor of safety to this rate to arrive at a proposed inspection interval of every eight days per wheelset,” she wrote.

From Washington Post • Nov. 4, 2021

The regulations and factor of safety requirements aren’t as strict because, if it fails, no one is going to die.

From Scientific American • Jul. 31, 2015

“The factor of safety is now back to being a high criterion when selecting an airline.”

From Time • Mar. 6, 2015

When following this plan gives a thinner tooth than the calculation calls for, the factor of safety and the allowance for wear are reduced.

From Modern Machine-Shop Practice, Volumes I and II by Rose, Joshua

The factor of safety used in this structure was four, but some engineers who are not familiar with concrete construction may require a higher factor.

From Transactions of the American Society of Civil Engineers, Vol. LXX, Dec. 1910 A Concrete Water Tower, Paper No. 1173 by Kempkey, A.