What is Heinrich’s law?
Herbert W. Heinrich, an insurance engineer, proposed in *Industrial Accident Prevention* (1931) that of 330 similar accidents to the same person, 1 causes major injury, 29 minor injuries and 300 no injury, the 1:29:300 ratio often drawn as a safety pyramid.
📌 At a glance
- Proposed by
- Herbert W. Heinrich (1931)
- Ratio
- 1 major : 29 minor : 300 no-injury
- Lesson
- Warning signs precede serious accidents
- Related
- Domino theory
Domino theory and criticism
Heinrich described five dominoes ending in injury and stressed removing unsafe acts and conditions. Critics note that his source data were never published, that he over-attributed accidents to worker behaviour, and that reducing minor incidents does not necessarily prevent fatal ones. Modern safety management keeps near-miss reporting but treats accidents as system and organisational failures.
Frequently asked questions
- What is Heinrich’s law?
- The idea that one major injury is preceded by about 29 minor injuries and 300 no-injury incidents.
- Is the 1:29:300 ratio reliable?
- The ratio itself is disputed, but the lesson to act on near misses remains widely used.
References
- Heinrich, H. W. (1931). Industrial accident prevention: A scientific approach. McGraw-Hill.
- Manuele, F. A. (2011). Reviewing Heinrich: Dislodging two myths from the practice of safety. Professional Safety, 56(10), 52–61.