LTIFR and TRIFR Calculator: Injury Frequency Rates per Million Hours

Lost time and total recordable injury frequency rates per million hours worked, with the average days lost per lost time injury.

Calculated from standard textbook formulas, with every step shown. The formulas are fixed, so the working does not need checking: what matters is the numbers you type in. Use these calculators only if you are competent to choose the inputs (loads, material strength, dimensions, supports) and check your units and assumptions. For learning and checking your own working: design and sign-off are for a qualified engineer. Drafting Central does not store the numbers you type.

How this calculator works

Enter the number of lost time injuries, the number of recordable injuries (including the lost time ones) and the total hours worked by everyone in the period.

The calculator gives the LTIFR and the TRIFR per million hours worked, the hours worked for each lost time injury, and the average days lost if you enter the days lost.

Check the definitions in your contract or in AS 1885.1, and whether the tender wants rates per million, 200,000 or 100,000 hours, before you compare figures.

Formulas used

  • \mathrm{LTIFR} = \frac{\text{lost time injuries}\times10^6}{\text{hours worked}}
  • \mathrm{TRIFR} = \frac{\text{recordable injuries}\times10^6}{\text{hours worked}}

Worked example

With the default numbers in the calculator above:

  1. Lost time injury frequency rate (LTIFR): 11.11 per million hours
  2. Total recordable injury frequency rate (TRIFR): 27.78 per million hours
  3. Average days lost per lost time injury: 15.00 days
  4. Hours worked for each lost time injury: 90000.00 hours

Change the numbers in the calculator to see the full working, every step, for your own case.

Common questions

What is LTIFR?

The lost time injury frequency rate is the number of lost time injuries for each million hours worked. It lets you compare periods and businesses of different size.

What is the difference between LTIFR and TRIFR?

LTIFR counts only injuries that cost time off work. TRIFR counts all recordable injuries, such as those needing medical treatment, so it is higher and picks up the less severe ones.

What is a good LTIFR?

It depends on the industry and how the injuries are defined. Compare it with your own history and with the figures your industry publishes, and read it with leading measures.

Why do small businesses have swingy rates?

With few hours worked, a single injury moves the rate a lot. A rolling 12 month figure smooths this.

Related calculators

Got a question about this? Ask an engineering question and get a plain-language answer with references.

Further reading: AS 1885.1 Workplace injury and disease recording standard; Safe Work Australia work health and safety statistics definitions.

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