Murphy’s Law

You may have heard of Murphy’s Law as “Anything that can go wrong, will.”
There is much more to it than that.

These laws were first collected in “The Contributions of Edsel Murphy to the Understanding of the Behaviour of Inanimate Objects,” by D.L. Klipstein in EEE Magazine, in the 1960s. Here’s just a sample:


  • In any given miscalculation, the fault will never be placed if more than one person is involved.
  • Any error that can creep in will. It will be in the direction that will do the most damage to the calculation.
  • A decimal will always be misplaced.
  • In a calculation with multiple plus-minus errors, the total error will be the sum of all errors adding in the same direction.


  • Specified environmental conditions will always be exceeded.
  • Any safety factor set as a result of practical experience will be exceeded.
  • Murphy’s Law supersedes Ohm’s.


  • Any component cut to length will be too short.
  • The availability of a component is inversely proportional to the need for that component.
  • If a project requires n components, there will be n-1 in stock.
  • Interchangeable parts won’t.
  • Components that must not and cannot be assembled improperly will be.
  • A component protected by a fast-acting fuse will protect the fuse by blowing first.
  • After the last of 16 mounting screws has been removed from an access cover, it will be discovered that the wrong access cover has been removed.
  • After an access cover has been secured by 16 hold-down screws, it will be discovered that the gasket has been omitted.

Last Reviewed: 5 years