Lost Time Injury Incidence Rate

What Does Lost Time Injury Incidence Rate Mean?

Lost time injury incidence rate (LTIIR) refers to the number of lost time injuries (LTIs) within an organization or workplace, relative to the number of employees, calculated over a specified time period.

Although similarly name, LTIIR differs from lost time injury frequency rate (LTIFR):

• LTIFR calculates the number of LTIs relative to the number of hours worked
• LTIIR calculates the number of LTIs relative to the number of employees

Safeopedia Explains Lost Time Injury Incidence Rate

While each are distinct, both the LTIIR and LTIFR are calculated using the same data. But rather than using hours as a standardizing factor for the rate, the standardizing factor for the LTIIR becomes a number of employees (typically 100). This means that calculating the LTIIR will reveal the number of lost time injuries experienced per 100 employees.

How to Calculate Your LTIIR

If you wanted to know the LTIIR for a certain time period, you would first need to know the number of long term injuries that occurred during that time, as well as the number of employees in the organization.

From there, you can use this formula to calculate your LTIIR:

LTIIR = (LTIs x 100) / (Number of Employees)

For example, let’s say there were 5 lost time injuries during the last quarter in a workplace with 367 employees. The LTIIR for that quarter will be:

5 x 100 = 500

500 / 367 = 1.36

Which means there were 1.36 LTIs per 100 employees during that time period.

An LTIIR of 1.36 can also be expressed by saying that, for ever 100 employees, 1.36 experienced a lost time injury.