Problem Severity Calculation Formula

The Mike Nakis formula for calculating the severity of a problem:

S = I × G × T


  • S is the severity of the problem.
  • I is the impact of the problem.
  • G is the geographic pervasiveness of the problem.
  • T is the temporal pervasiveness of the problem.


  • A high-impact problem need not be regarded as severe if it happens rarely and in only a few places.
  • A low-impact problem should be regarded as quite severe, if it is persistent and widespread.

For example: 

The sinking of the Titanic was certainly a disaster, but it was largely an isolated incident: it happened only once, on the 15th of April 1912, and only in one place, at 41°43′32″N 49°56′49″W; we have not had anything quite like that happening before, and we have been doing a decent good job avoiding similar incidents ever since, so in the big picture, it is not a particularly severe problem.

On the other hand:

A computer taking several long seconds to reboot, despite having a multi-core, multi-gigahertz, hyper-threaded and pipelined CPU with multi-level cache and solid-state storage, is a problem which affects everyone, everywhere, every day, so it is in fact a severe problem.

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