How to Calculate TRIFR, LTIFR and Other Health and Safety Indicators

by Barry Spud on October 11, 2016

in Safety Statistics,Workplace Safety

How to Calculate TRIFR, LTIFR and Other Workplace Health and Safety Indicators

****** REMEMBER ZERO REPORTED INJURIES DOES NOT EQUAL SAFETY ****** This is a dangerous illusion!!

Download our Free Injury Data and Statistics Spreadsheet

First some other articles which perhaps you should read before worrying about calculating LTIFR to 5 decimal places:

Courage to Challenge the Great TRIFR and LTI Delusion
Courage to Challenge the Great TRIFR and LTI Delusion It was Marx (The German Ideology) who said ‘as individuals express their life, so they are’. At the heart of this aphorism is the idea that what is normalized in a culture comprises what the culture is. One of the things that have become normalized in the culture …… Enjoy the rest of the article >>>>>

LTIFR – A Measure of Safety Performance?

Bizarre… definitely but not quite as bizarre as the wide spread use of the Lost Time Injury Frequency Rate or LTIFR which is an almost …

Difficulties Calculating LTIFR and Other Safety Indicators • Safety Risk

The difficulties often encountered when calculating LTIFR and other safety indicators are not with the calculation itself but with the data.

Lost Time Injury Frequency Rate • Safety Risk

The Lost Time Injury Frequency Rate is the principal measure of safety performance in many companies in Australia. The definition of

More on 10 Sure Fire Ways To Stuff Up a Safety Management System

Some safety people cheat like hell with their L.T.I.F.R. statistics encouraged by managers with an eye to keep their key performance indicators …– management-system/

How to Calculate LTIFR and Other Health and Safety Indicators

LTIFRKnowing how to calculate LTIFR and other safety indicators is an important skill to have if you work in the health and safety field. Despite the fact that these indicators don’t reveal a great deal of useful information managers love them and will insist on knowing what they are. They will use them to measure internal health and safety performance and to compare you’re company’s performance with other companies. These are not difficult to calculate and this can be made even easier if you use a spread sheet.

LTIFR and other Health and Safety Indicators

Broadly speaking, common health and safety indicators can be divided into two – frequency rates and incidence rates. So what’s the difference?

A frequency rate is an expression of how many events happened over a given period of time by a standardised number of hours worked. An incidence rate is the number of events that happened over a given period time by a standardised number of employees (usually lower than the standardised number of hours). For example, an LTIFR which stands for Lost Time Injury Frequency Rate, is the number of Lost Time Injuries (LTI) that occurred over a period time per 1 000 000 or 100 000 or some other number of hours worked in that period. This could be over a month or a quarter or a year depending on the reporting requirements of your business. To convert this to an incidence rate just substitute the number of employees for the number of hours.

A lot of things are presented in this manner. As well as lost time injuries there are Medical Treatment Injuries (MTI) another is significant injuries which are often categorized as LTIs plus MTIs. A slight variation is the severity rate which is usually a measure of the amount of time lost due to work related injury by some standardised figure that is used to indicate the severity of injuries.

Calculating Frequency Rates

The formula to calculate these indicators is really very simple. Let’s say we want the number of lost time injuries per 1 000 000 hours worked for the last year. You need to get two pieces of information – the number of LTIs that happened in the last year and the number of hours worked in the last year. You could probably get the number of LTIs from your workers compensation claims manager or insurance company and your payroll section should be able to tell you the number of hours worked over the period.

Multiply the number of LTIs by 1 000 000 and divide the result by the number of hours worked and there you have it – the LTIFR. To show it using numbers. Say there were 7 LTIs in the past year and 2 451 679 hours worked. So, 7 X 1 000 000 = 7 000 000. Divide that by 2 451 679 and you get 2.86 – go on, grab your calculator and try for yourself.

What does that mean? It means that this business experienced 2.86 LTIs for every 1 000 000 hours worked over the past year.

Calculating Incidence Rates

Now, to calculate the LTIIR (Lost Time Injury Incidence Rate) which is the number of LTIs per 100 (or whatever figure you want) employees we just substitute the number of employees for the number of hours and multiply the number of LTIs by the standardizing factor which is 100.

So say this mythical business had 791 employees, we get 7 X 100 = 700. Divide this by the number of employees – 791 – and we get 0.88. So for every 100 employees this firm experienced 0.88 LTIs.

Calculating Severity Rates

Finally the severity rate. Depending on how this is expressed you will need at least the information from above and the number of work days lost over the year. Say its 73. Most often the severity rate is expressed as an average by simply dividing the number of days lost by the number of LTIs. So, using the figures we have we get 73 divided by 7 which gives 10.43. That is, on average each LTI will result in 10.5 days off work. It can be converted to a frequency or incidence rate by multiplying the result by a standardizing factor. This, of course will increase the result which is why you don’t see it very often – who wants a severity rate of 104 days off per 100 LTIs?

So there you have it. Not very hard and if you know even a little bit about spreadsheets you can easily insert the formulas into specific cells to calculate these indicators automatically.

Barry Spud

Barry Spud

Safety Crusader, Zero Harm Zealot and Compliance Controller at Everything Safety
Barry Spud
What is a Safety Spud? Lets look at a few more spud head activities in risk and safety: 1. Coming on to site saying there is a safety issue when in fact there’s no such thing, it’s a political issue. 2. ‘Falling apart’ when people make choices that we think are stupid because they won’t do as we ‘tell’ them. Then we put on the angry face and think that overpowering others creates ownership. 3. Putting on the zero harm face, presenting statistics, knowing it has nothing to do with culture, risk or safety. 4. Putting on the superman (hazardman) suit and pretending to be the saviour of everything, this is good spud head cynic stuff. 5. Thinking that everyone else is a spud head except me. 6. Thinking there’s such a thing as ‘common’ sense and using such mythology to blame and label others. 7. Accepting safety policies and processes that dehumanize others. 8. Blaming, ego-seeking, grandstanding and territory protecting behind the mask of safety. 9. Thinking that risk and safety is simple when in fact it is a wicked problem. Denying complexity and putting your spud head in the sand. 10. Continually repeating the nonsense language and discourse of risk aversion that misdirect people about risk, safety, learning and imagination.
  • Collette Dowling

    Hello there, just wondering if you could help clear up a query for me.
    We have only in 2016 started doing reports on LTIFR here in our job in Ireland. We prepare reports monthly using your calculation for LTIFR and have no issue with this. The question arises when you say get to second month of year or more, how you calculate your LTIFR? Lets say we have 1 LTI in Jan and 1 in February. I would add the 2 LTI’s together and get 2 and then divide this by the combined number of hours worked for Jan and February and multiply by 100K. Is this correct? My Manager is saying that calculation is done monthly to get LTIFR and then you add up all the LTIFR and get the number. Which is correct?

    See chart below:
    LTIFR : Per 100,000 Hours worked
    2016 No of LTI No of hours Worked LTIFR
    Dec 0 9005 0
    Jan 1 7313 13.67
    Feb 0 10063 0
    Mar 0 16541 0
    April 0 3649 0
    May 0 3656 0
    June 0 6228 0
    July 0 6228 0
    Aug 0 6400 0
    Sept 1 6400 15.63
    Oct 1 11460 8.73
    Nov 0 10156 0
    Totals 3 97099 ?

    I get 3.09 LTIFR however my boss says we add these and it should be 38.03.

    You help or opinion would be greatly appreciated.

    Thank you.

    • How on earth can you calculate or measure safety to two decimal places? I know why people think they have to do it, because it’s easy, but it is a completely meaningless attempt to quantify something that cannot be measured. Please have a read of – I hope it helps you to do some critical thinking on this and convince your boss of what a silly, counterproductive waste of time it is!!! There are many more important things we can do for safety like having meaningful conversations about risk and discerning the by-products of meaningless measuring (ie non-reporting)

  • KINGSLEY efekalam

    please what is the formular for calculating Medical treatment injury frequency rate? MTIFR

    • This frequency rate measures how often medical treatment injuries are occurring. It is expressed as the number of medical treatment injuries per million hours worked.
      Number of medical treatment injuries/by Number of hours worked x 1,000,000

      May depend on your jurisdiction

  • Alonso Pirela

    Hello, Tom Gardener

    Could you please tell me where these indicators come from?

    I mean, what is the international standard who regulate all of this calculation. Because I am looking the begining of this calculation.

    Thanks for yor help

  • Sydney Wait

    Hi, can you please mail me how to calculate the incident frequency rate. I know its something times something over something times something.Thanks

    • Those somethings are described in the article?

  • Thanks you George and Thank you Rod.
    Much appreciated.

  • Rod Taylor

    As George has shown they are all exactly the same formula you just change the metric that you are looking to track. I have seen AIFR to mean All Incident Frequency Rate as well as All Injury so it is up to you depending what you want. I found the all incident to be a better measure as it includes near hits, equipment damage and all the non injury incidents that occur



  • Australian Standard 1885, Recording and Measuring Work Injury Experience is the bible and I would suggest you look there.
    L.T.I.F.R.=No. Lost Time Injuries X a milion, divided by the manhours exposure I gave up using frequency rates for first-aid and all injuries a long time ago because the are meaningless and I am not 100% sure of the formula.
    I think it is
    No. first aid cases X a million, divided by the manhours exposure
    Total number of injuries X a milllion, divided by manhours exposure
    All these measures, including L.T.I.F.R. are prety dodgy and should be supplemented by positive performance indicators.

  • Hi

    I am filling our a form at the moment and this is all new to me.
    It asks for the following
    1. LTIFR – Lot Time Injury Frequency Rate – I have a formula for this
    2. MTIFR – Medically Treated Injury Frequency Rate – I have a formula for this
    3. FAIFR – ?????? – I can’t find a formula for this
    4. AIFR – ????? – I can’t find a formula for this

    If you are able to help me with 3 and 4 and a formula for each that would be great.

    Thanks in advance

  • Rod Taylor

    Australian Standard AS1885.1 Definitions Clause 3.5 – “Those occurences that resulted in a fatality, permanent disability or time lost from work of one day/shift or more”.

    Not sure why SafeWork have decided to report on something different. Either way just because they do doesn’t mean I, or anyone else, have/has to. The standard is as above

    • Mike Littlely

      OK I have changed my spreadsheet/ Safety Stat to conform to the Australian Standard.

      Its pointless now to compare my figures against that list of industry stats

  • Rod Taylor

    Mike it obviously depends on where you are. Australian Standard defines an LTI as the first full shift off work. Nothing to do with Workers comp and most definately not a week.

    I once worked for an organisation that tracked on a per hour basis. Any time taken off work due to a work injury was included and reviewed at the end of the month or week depending on the level of management it was.

    • Mike Littlely

      Scope: All accepted workers’ compensation claims with one week or more time lost excluding travel to and from work
      Frequency rates are expressed as a rate per million hours worked.

      Source: Safe Work Australia National Data Set for Compensation-based Statistics (NDS).

      This is where I got my info
      Any comments?

  • Definition of a LTI

    I find it hard to believe that we don’t classify an injury as a LTI until it becomes an accepted workers comp claim of over a week.
    Is this the standard or have I got it wrong

  • wasim shaikh

    how to calculate accident frequency rate please brief in example

  • Andre Krog

    Where can I found the LTIFR for other coal mines. I want to benchmark our statistics to those of other groups outside of South Africa

  • “@Riskex: How to Calculate LTIFR and Other Health and Safety Indicators via @Riskex”

  • How to Calculate LTIFR and Other Health and Safety Indicators via @Riskex

Previous post:

Next post: