What is the formula for LTIR?

LTIR equals the number of lost-time cases, days-away cases, times 200,000, divided by total hours worked. Using the same running example, 1 lost-time case across 400,000 hours worked gives an LTIR of 1 times 200,000 divided by 400,000, or 0.5. The formula is identical to TRIR’s; only the numerator changes. Instead of every recordable case, LTIR counts only the cases serious enough that the worker missed at least one full scheduled day. That narrower numerator is why LTIR is almost always a smaller number than TRIR calculated from the same hours.

Why is LTIR always less than or equal to TRIR?

Because every lost-time case meets the definition of a recordable case, but not every recordable case involves a day away from work. A worker who needed stitches and returned to full duty the same shift is recordable but not lost-time. A worker who missed the next day is both. Since LTIR’s numerator is always a subset of TRIR’s numerator over the identical hours denominator, LTIR is mathematically bounded by TRIR. It can equal TRIR only in the rare case where every recordable happened to also be a lost-time case, and it is usually meaningfully lower.

How does LTIR differ from DART?

LTIR counts only days-away cases. DART counts days-away cases plus restricted-work and job-transfer cases, so DART sits between TRIR and LTIR in scope: wider than LTIR because it includes restrictions that don’t involve missing a day, narrower than TRIR because it excludes recordables that were treated and released with no restriction at all. A firm can have a DART rate noticeably higher than its LTIR if it has many restricted-duty cases that never produced a day away, which is a meaningful difference for anyone comparing two contractors’ safety records side by side.

Construction Glossary · Safety

Lost TimeIncident Rate

Every lost-time case is a recordable case. Not every recordable case is lost-time. LTIR measures only the subset serious enough to keep someone off the job.

Definition

Lost-time cases, injuries serious enough to keep someone away from work, times 200,000 divided by hours worked. LTIR is the severe subset of TRIR: every lost-time case is also a recordable case, so LTIR can never exceed TRIR, and the gap between the two shows how much of the recordable total is genuinely serious.

The subset inside TRIR

On the same 400,000 hours, TRIR of 1.5 covers all 3 recordables; LTIR of 0.5 covers only the 1 case that kept a worker off the job. LTIR can never be drawn wider than the TRIR bar it sits inside. That containment is not a coincidence of this particular example; it is guaranteed by the definitions themselves, since a days-away case always clears the lower bar of being a recordable case first, which is why the LTIR bar can shrink toward zero but never grow past the TRIR bar beside it.

One set of cases, three rates

The same 3 recordables and 400,000 hours produce a different number depending on which numerator you use. Reporting only one of the three invites the reader to assume it stands in for the others, which it never safely does, since a low LTIR can still sit next to a high TRIR driven by cases that never produced a lost day.

Rate	Numerator in this example	Result
TRIR	All 3 recordable cases	1.5
DART	2 cases: 1 days-away + 1 restricted/transfer	1.0
LTIR	1 days-away case only	0.5

Each row starts from the same recordable incident count. TRIR and DART just draw the line in different places.

How POD surfaces LTIR

POD computes LTIR from the lost-time case count and the hours worked when both are present, and surfaces it alongside TRIR and the lost-time count, gated to those two inputs, with a placeholder when either is missing. The arithmetic is simple and deterministic, lost-time cases times 200,000 over hours, so the figure is a direct read of your own records, not an estimate.

TRIR vs EMR vs LTIR vs DART guide

Frequently asked questions

LTIR is the narrowest lens

Add back the restricted and transfer cases LTIR leaves out, and the rate that fills that middle ground, wider than LTIR but narrower than TRIR, is DART.

DART Rate Back to the Glossary

Related terms

TRIR DART Recordable Incident EMR