TRIR, DART & LTIFR Explained: Formulas, Examples, and How to Benchmark
Quick answer: Incident rates standardize your injury numbers so a 30-person shop and a 3,000-person plant can be compared fairly. Each rate is (number of cases × 200,000) ÷ total hours worked. TRIR uses all recordables, DART uses days-away/restricted/transfer cases, and LTIFR uses lost-time cases. Run yours in seconds with our free incident rate calculator.
Why these numbers matter
Incident rates aren't just paperwork. They feed your experience modification rate (EMR) and workers'-comp premiums, they're requested on bids and prequalification questionnaires (many clients won't let a contractor on site above a threshold TRIR), and they're how leadership tracks whether safety is improving. Getting them right — and improving them — has real dollars attached.
The formula (and what 200,000 means)
Every OSHA incidence rate uses the same structure:
Rate = (Number of cases × 200,000) ÷ Total hours worked by all employees
The 200,000 is the number of hours 100 full-time employees work in a year (100 workers × 40 hours × 50 weeks). It normalizes the rate so it reads as "cases per 100 full-time workers per year" — which is why two companies of very different sizes can be compared.
TRIR — Total Recordable Incident Rate
Uses your total OSHA recordable cases (everything on the 300 log). It's the headline number most people mean by "our incident rate."
DART — Days Away, Restricted, or Transferred
Uses only the cases that resulted in days away, restricted work, or a job transfer — the more serious subset. DART is always less than or equal to TRIR and is a better signal of severity.
LTIFR / LTC — Lost-Time cases
Uses cases with days away from work only. Sometimes called the lost-time case rate, it isolates the injuries serious enough to keep someone off the job.
A worked example
A plant with 120 employees works about 240,000 hours in a year and has 4 recordables, 2 of which involved days away or restriction:
- TRIR = (4 × 200,000) ÷ 240,000 = 3.33
- DART = (2 × 200,000) ÷ 240,000 = 1.67
How to get your total hours
Use actual hours worked from payroll — not hours paid (exclude vacation, holiday, and sick leave). If you must estimate, multiply headcount by scheduled hours: e.g., 120 employees × 40 hours × 50 weeks = 240,000. Always use the same period for cases and hours.
Benchmarking: what's a "good" rate?
"Good" is relative to your industry. The Bureau of Labor Statistics (BLS) publishes injury and illness incidence rates by NAICS code each year — find your code and compare. As a rough orientation, recent private-industry TRIR sits around 2–3, with manufacturing and warehousing typically higher. The goal is to be below your industry average and trending down.
The limitations (don't over-read them)
Rates are lagging indicators — they tell you what already happened. They're also volatile at small headcounts, where one injury swings the rate dramatically. Pair them with leading indicators like near-miss reports, audits, and training completion to see the full picture.
Try the free calculator
Skip the spreadsheet math: our Incident Rate Calculator computes TRIR, DART, and LTIFR and shows how you compare to industry benchmarks — with a built-in estimator if you don't have your total hours handy.
Key takeaways
✓ Every rate = (cases × 200,000) ÷ hours worked.
✓ 200,000 = 100 full-time workers for a year, so the rate reads "per 100 workers."
✓ TRIR = all recordables; DART = days-away/restricted/transfer; LTIFR = lost-time only.
✓ Use actual hours worked, and benchmark against your NAICS code in BLS data.
✓ Rates lag — pair them with leading indicators.
Build It Into Your Safety Program with Vetted Safe
Knowing the rule is half the battle — doing it consistently is the rest. Vetted Safe's Incident & Accident module captures the data as the work happens, so your records build themselves and nothing slips through the cracks.
Explore the HSE platform or see plans and pricing to put your whole safety program in one place.