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

And because that "factor of safety" is a large one with respect to the normal benzoic acid content of our food it does not follow that we can encroach on it with perfect impunity.

From Food Poisoning by Jordan, Edwin Oakes

That substructures and retaining walls designed according to the Rankine or similar theories have an additional factor of safety from too generous an assumption in regard to earth pressure is practically admitted everywhere.

From Pressure, Resistance, and Stability of Earth American Society of Civil Engineers: Transactions, Paper No. 1174, Volume LXX, December 1910 by Meem, J. C.