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

In general, some considerable factor of safety must be allowed after arriving at calculated average of samples,—how much it is difficult to say, but, in any event, not less than 10%.

From Principles of Mining Valuation, Organization and Administration by Hoover, Herbert