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March 7, 2019

What Is Lost Time Injury, How Do You Calculate It and Why Should You Track It?

As an environmental, health and safety leader, your job requires you to collect a variety of metrics that give you a data-driven look at your safety program. These metrics provide details on specific areas and give you a better idea of where to direct your efforts. One of the most important metrics you should pay attention to is the Lost Time Injury rate.

Also known as Lost Time Incident or Lost Time Case, Lost Time Injury (LTI) is one of several metrics you’ll want to track in your EHS department. These metrics work together to give leaders a detailed look at their safety program’s effectiveness.

Here’s what you need to know about Lost Time Injury rate and how it affects your overall safety record.

What Is Lost Time Injury?

Lost Time Injury refers to incidents that result in a disability or an employee missing work due to an injury. Employees who return to work after sustaining an injury may also be counted as a Restricted Work Injury if they are unable to completely perform their job duties as outlined in their job description. Also, only injuries deemed to be work related will count as a Lost Time Injury. Accidents that happen off the clock that affect an employee’s ability to work will not be counted in this metric.

The resulting figure represents the number of lost time injuries in a given period compared to the total number of hours worked during that period. This is considered a “lagging indicator,” as the figure is calculated after incidents have already occurred to give hindsight into your EHS performance. This means that LTI are not a perfect predictor of a company’s future safety performance, but rather shows companies what happened in a given timeframe so they can take steps to prevent similar incidents in the future.

Why It Matters

The higher this measurement, the greater the indication that your safety performance is lacking. Indications of poor safety performance could result in higher insurance premiums. Your best workers may start looking for employment elsewhere under the belief they’re at safety risk while at work.

Also, numerous incidents that are serious enough to result in lost time could lead to bad PR for your company and give you a reputation that will be hard to change.

Granted, a “high” or “low” number can be relative, as safety looks different depending on the industry. It’s important to compare your numbers to companies in your own industry to create a benchmark for your own performance. Ideally, you’ll want to achieve a lower figure than others in the industry.

How to Calculate Lost Time Injury Rate

Lost Time Injury rate follows a simple formula to indicate your performance. Divide the total number of lost time injuries in a certain time period by the total number of hours worked in that period, then multiply by 200,000 to get the LTIR. This number tells you the number of lost time injuries per 100 worker years (equivalent to 2000 hours worked for each of 100 workers).

Note, some companies in certain countries use 1,000,000 instead of 200,000 in the formula described above. The reason for using such large numbers is the number of lost time injuries compared to total number of hours worked is always small. Using a larger number as a baseline makes it easier to interpret. It looks like this:

(LTI / Total # Hours) x 200,000

For simplicity’s sake, let’s say you ended the year with two lost time injuries out of 150,000 man hours worked. The LTI metric result would be 2.67.

The gravity or severity of the injury is not calculated in this metric. Rather, it’s only concerned with the number of injuries, not the amount of time lost due to each injury or other contributing details. Many companies see a strong correlation between their LTIR and their Experience Modification Rate (EMR), which is used by insurance companies to measure both past cost of injuries and future risk. The lower the EMR of your business, the lower your worker compensation insurance premiums will be. LTIR helps you see potential changes in EMR before the insurance company makes adjustments.

Prevention Matters Most

It’s easy to get caught up in safety metrics and data, but don’t let your metrics make you lose sight on what’s most important. Preventing injuries is the main goal, regardless of how good your Lost Time Injury numbers look.

Strengthening your safety program should take priority over any metric. As long as you’re focusing on providing a safe work environment for your employees, your metrics will most likely reflect it.

Further readingHow to Calculate Total Recordable Incident Rate 


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