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

Just as an added factor of safety, you'd better put this on, Clio—those emergency suits aren't good for much in a battle.

From Triplanetary by Smith, E. E. (Edward Elmer)

But for every departure from this, which they deem the best mode of construction, a penalty in the shape of an addition to the factor of safety is made.

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