Knowing 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.

**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.