TRIR = (OSHA-recordable cases × 200,000) ÷ total hours worked. DART uses only cases involving days away, restriction, or transfer; LTIR uses lost-time cases. The 200,000 constant represents 100 full-time workers at 40 hours for 50 weeks, which is what makes rates comparable across company sizes. This free calculator returns all three rates and benchmarks them against approximate BLS 2023 private-industry averages (TRIR ≈ 2.4, DART ≈ 1.5).
These rates drive ISNetworld and Avetta grades, general-contractor prequalification, and insurance experience rating — the same numbers, scored four different ways.
The BLS private-industry average is roughly 2.4 (2023); below that is competitive, and below about half of it is the range that earns strong ISN grades and insurance credits. Industry-specific averages differ substantially — compare against your own NAICS code in the BLS Survey of Occupational Injuries and Illnesses.
Total recordable cases from your OSHA 300 log, multiplied by 200,000, divided by total hours worked by all employees in the year. DART is calculated the same way using only cases with days away from work, job restriction, or transfer.
They're the standard normalized safety performance measures from OSHA recordkeeping data — hiring clients use them to screen contractors, often with hard cutoffs, and insurers use the same underlying cases to set your experience modification rate.