A Guide to Tracking & Calculating Lost Time Incident Rate (LTIR)

There’s no shortage of metrics to capture in your environmental, health and safety strategy. Figuring out which ones can make the biggest impact can seem daunting, but many of them are critical to your organization’s success. When creating your EHS strategy, recording your Lost Time Incident Rate (LTIR) should be a priority.

Frequently Asked Questions

• What is Lost Time Incident Rate (LTIR)?

  • LTIR — Lost Time Incident Rate — is an OSHA metric that measures the number of workplace incidents resulting in an employee missing one or more workdays per 100 full-time workers. It focuses specifically on incidents severe enough to cause an employee to be absent from work.

• How is LTIR calculated?

  • The LTIR formula is: (Number of Lost Time Cases × 200,000) ÷ Total Hours Worked. The 200,000 constant normalizes the rate for comparison across organizations of different sizes, representing 100 employees working 40 hours per week for 50 weeks.

• What is the difference between LTIR and TRIR?

  • TRIR includes all OSHA-recordable incidents, including those requiring only medical treatment beyond first aid. LTIR is narrower — it only counts incidents where an employee missed at least one day of work as a result of the injury or illness.

• What is the difference between LTIR and DART rate?

  • DART includes days away from work, restricted duty, and job transfers. LTIR focuses only on incidents that result in actual lost workdays (days away from work). DART is the broader of the two measures.

• Can LTIR be over-reported?

  • Unlike TRIR, LTIR is difficult to over-report because it only counts incidents resulting in actual lost workdays. This makes LTIR a more precise and reliable indicator of serious workplace injuries compared to metrics that include all recordable events.

• How does LTIR affect insurance premiums?

  • An increasing LTIR can directly trigger higher workers' compensation insurance premiums, as insurers view lost-time incidents as a signal of elevated risk. Conversely, a low and improving LTIR can be leveraged to negotiate more favorable insurance terms.

How to Calculate Lost Time Incident Rate

The Lost Time Incident Rate is calculated similarly to the TRIR metric we recently discussed.

(Number of lost time cases x 200,000) / total number of hours worked by employees

The figure 200,000 is a standard number to measure incident rates so companies of varying sizes can be compared fairly. This figure was determined by multiplying 100 employees by 40 hours (a standard work week) by 50 weeks (assuming each employee takes two weeks of vacation).

The resulting figure indicates the number of employees who lost time due to an incident.

For example, if you have 40 full-time employees and 3 incidents that resulted in lost time, your calculation will look like this:

(3 x 200,000) / 80,000 (40 employees x 40 hours per week x 50 weeks per year)

Your Lost Time Incident Rate would be 7.5, which means that for every 100 employees, 7.5 have experienced lost time due to an incident.

The Importance of Tracking Lost Time Incident Rate

It might sound like just another metric, especially if you’re already obligated by OSHA to record it. But even if no one is forcing your hand, this particular piece of data can prove beneficial to your company.

For starters, calculating your lost time incident rate lets you know how much impact those incidents have on your organization and if the trend is improving or worsening over time.

Your Lost Time Incident Rate may also affect your business insurance rates. An increase in this figure may trigger a series of other events, including a hike on your insurance premiums.

Another benefit is that this statistic is impossible to over-report, unlike recordable incidents. Some companies record incidents that shouldn’t be recorded for fear of becoming non-compliant with OSHA requirements. Reporting unnecessary incidents exaggerate your figures, since LTIR focuses only on incidents resulting in time away from work, there’s no way for you to skew the results so you get a more accurate idea of your safety status.

Making the Most of Lost Time Incident Rate Reporting

LTIR is a lagging indicator, meaning it uses data from incidents that have already happened. This figure on its own can’t help you forecast future incidents, but it can prove useful over time.

Many medium- and large-sized companies calculate this rate monthly and track the trends from month to month. You can compare this rate to activities in your safety program to help gauge their effectiveness. For example, if you implement a new form of training at the beginning of the year and notice your LTIR decreases from the previous year, you might be inclined to believe your safety training had something to do with it.

EHS software can help you track this rate automatically to give you an up-to-the-minute look at your current status. If you notice your rate starts to climb, you’ll know to investigate it sooner than later. If they decline, you’ll know something in your safety program is working.

For more insight on how to strengthen your EHS programs, visit our blog resources.