TRIR Calculator: OSHA Incident Rate, DART Rate and LTIR

What does this TRIR calculator work out?

This TRIR calculator turns your injury log and hours worked into four standard rates. Each one uses the same structure: a case count, multiplied by a base number of hours, divided by the hours your employees actually worked.

• TRIR: recordable cases × base ÷ hours.
• DART rate: DART cases × base ÷ hours.
• LTIR / LTIFR: days-away (lost-time) cases × base ÷ hours.
• Severity rate: lost or restricted workdays × base ÷ hours.

On the 200,000-hour base, the calculator also shows the latest US private-industry average from the Bureau of Labor Statistics (BLS) next to each comparable result.

What is TRIR?

TRIR stands for total recordable incident rate. It is the number of OSHA recordable injuries and illnesses per 100 full-time workers over a period, usually a calendar year.

BLS publishes the same measure as the "total recordable cases" incidence rate. Because it adjusts for hours worked, it lets a 40-person shop and a 4,000-person plant be compared on a common footing.

How do you calculate TRIR?

BLS gives the formula on its incidence rate guide:

TRIR = (number of recordable cases × 200,000) ÷ employee hours worked

Count recordable cases from your OSHA 300 Log, or add columns H, I and J on the OSHA 300A summary. For hours, BLS says to exclude non-work time even when it is paid, such as vacation, sick leave and holidays.

Here is a worked example with clean numbers. A site has 250 employees working 2,000 hours each, so 500,000 hours in the year. It logged 6 recordable cases, 3 DART cases, 2 days-away cases and 45 lost workdays.

• TRIR = 6 × 200,000 ÷ 500,000 = 2.4
• DART rate = 3 × 200,000 ÷ 500,000 = 1.2
• LTIR = 2 × 200,000 ÷ 500,000 = 0.8
• Severity rate = 45 × 200,000 ÷ 500,000 = 18.0 lost days per 100 workers

On the 1,000,000-hour base, the same 2 lost-time cases give an LTIFR of 2 × 1,000,000 ÷ 500,000 = 4.0. Enter these values in the TRIR calculator to check the arithmetic.

What is a good TRIR?

Once the TRIR calculator gives you a number, the most useful benchmark is your own industry. For context, the BLS 2024 release reports these private-industry rates per 100 full-time equivalent workers:

Measure (2024, US private industry)	Rate
Total recordable cases (TRIR)	2.3
DART cases	1.4
Cases with days away from work	0.8
Cases with job transfer or restriction only	0.5

The industry spread is wide. In the same release, the information sector had a TRC rate of 0.7, while health care and social assistance had 3.4. Look up your NAICS code in BLS Table 1 of industry incidence rates before deciding whether your result is good or bad.

DART rate vs TRIR vs LTIR: what is the difference?

All three use the same formula but count different cases:

• TRIR counts every recordable case, including those treated at work with no time lost.
• DART rate counts cases with days away, restricted work or job transfer. BLS defines DART as days-away cases plus cases with only transfer or restriction.
• LTIR (or lost time injury frequency rate, LTIFR) counts only cases where the worker lost time away from work.

So DART is always a subset of TRIR, and lost-time cases are a subset of DART. A severity rate is different again: it measures days lost, not cases.

What counts as a recordable injury?

Under 29 CFR 1904.7, a work-related injury or illness is recordable if it results in death, days away from work, restricted work or job transfer, medical treatment beyond first aid, or loss of consciousness. A significant diagnosed case, such as a fracture, a punctured eardrum, cancer or a chronic irreversible disease, is also recordable.

First aid is a defined list. It includes non-prescription medication at non-prescription strength, cleaning wounds, bandages, hot or cold therapy and non-rigid supports. Days away are counted in calendar days starting the day after the injury, and you may cap the count at 180.

Why 200,000 hours?

BLS explains that 200,000 hours equals 100 employees working 40 hours a week for 50 weeks a year. That is why every result from an OSHA incident rate calculator reads as cases per 100 full-time workers.

Outside the US, a base of 1,000,000 hours is common. Safe Work Australia, for example, publishes its injury frequency rates as claims per million hours worked. A rate on the million-hour base is five times the same rate on the 200,000 base, so never compare the two directly.

What are the limits of lagging indicators like TRIR?

TRIR, DART and LTIR all count harm after it has happened. They also swing sharply at small sites: with 100,000 hours a year, a single extra case moves TRIR by 2.0.

Safe Work Australia also notes that claim-based frequency rates underestimate injuries, because not every injury leads to a claim. Treat any TRIR calculator result as one signal, not proof of a safe workplace.

Musculoskeletal disorders often build up slowly before they ever reach the OSHA 300 Log. To catch risk earlier, screen jobs with our free ergonomic risk screening checklist and fold the findings into a structured workplace ergonomics program. For the regulatory side, see what OSHA expects on ergonomics, and for the business case, read what ergonomic injuries cost employers.