Injury Rate Calculator
A workplace's injury rates from its records — the total recordable rate per 200,000 hours, the lost-time frequency per million hours, and the severity rate — so that sites of different sizes can be compared.
Injury counts mean nothing without the hours worked, so safety rates normalise them: per 200,000 hours, which is about a hundred people for a year, or per million hours.
How the injury rate calculator works
Injury counts mean nothing without the hours worked, so safety rates normalise them: per 200,000 hours, which is about a hundred people for a year, or per million hours. Both conventions are in use — the first in North America, the second in Australia, Britain and much of industry — and the page shows both. The severity rate weights by days lost, which separates a site with many scratches from one with a few serious injuries.
Formula: TRIR = recordables × 200,000 / hours; LTIFR = lost-time injuries × 1,000,000 / hours; severity = days lost × 200,000 / hours
Worked examples
| Inputs | Total recordable rate (per 200,000 h) | Note |
|---|---|---|
| Five recordables in 400,000 hours | 2.5 | TRIR 2.5 |
| A safer year | 0.5 | TRIR 0.5 |
| A serious injury | 1 | low frequency, high severity |
FAQFrequently asked questions
What is a recordable injury?
One that needs treatment beyond first aid, causes lost or restricted work, or is otherwise reportable under the local regulator's rules. Definitions differ by jurisdiction; use yours consistently.
Why 200,000 hours?
A hundred full-time workers for a year — 100 × 40 × 50. The rate then reads as injuries per hundred workers per year, which is what OSHA-style reporting uses.
Why a million hours?
The convention in Australia, the UK and much of heavy industry for lost-time injury frequency. The two rates are the same measure scaled by five.
What is a good TRIR?
Under 1 is excellent; 2 to 3 is around the all-industry average in most developed countries; construction and manufacturing run higher. Compare within your sector.
Why track severity as well?
Because frequency counts a cut finger and an amputation alike. Days lost per 200,000 hours shows how serious the injuries are, and one bad one can dominate a year.
Where these figures come from
- Nakajima (1988) — Introduction to TPM — the origin of Overall Equipment Effectiveness and its six big losses
- Safe Work Australia — the national work health and safety body
Last checked: September 2026. Definitions follow standard operations-management practice; where plants commonly differ, the page says so.