How to calculate your TRIR and DART rates for OSHA 300A

TRIR and DART are the two incident rates most employers use to summarize OSHA recordkeeping performance. Both use the same basic formula: cases times 200,000, divided by employee hours worked. The difference is which cases you count.

OSHA describes the standard incidence-rate formula in a recordkeeping interpretation as:

(Number of injuries and illnesses x 200,000) / Employee hours worked

The 200,000 constant represents 100 full-time employees working 40 hours per week for 50 weeks. That lets a 35-person establishment and a 350-person establishment compare rates on the same basis.

What TRIR means

TRIR stands for Total Recordable Incident Rate. OSHA's public data often calls the same idea the Total Case Rate, or TCR.

For a Form 300A, use the total recordable cases from the annual summary. In current OSHA ITA data, that total is the sum of the case-classification columns:

• Cases with days away from work
• Cases with job transfer or restriction
• Other recordable cases

The formula is:

TRIR = (total recordable cases x 200,000) / total hours worked

Example: an establishment had 7 total recordable cases and 182,000 employee hours worked.

7 x 200,000 / 182,000 = 7.69

Its TRIR is 7.7 when rounded to one decimal place.

What DART means

DART stands for Days Away, Restricted, or Transferred. It is narrower than TRIR because it counts only the recordable cases that involved days away from work, restricted work activity, or job transfer.

For a Form 300A, use:

• Cases with days away from work
• Cases with job transfer or restriction

The formula is:

DART = (DART cases x 200,000) / total hours worked

Example: the same establishment had 4 DART cases and 182,000 employee hours worked.

4 x 200,000 / 182,000 = 4.40

Its DART rate is 4.4.

Where the numbers come from

The case counts come from your OSHA 300 log and roll up into the 300A annual summary. The hours-worked number is the total hours worked by all employees at the establishment during the calendar year. Do not use headcount in the denominator. Do not use payroll dollars. Do not use scheduled hours if your records show actual hours worked.

If you have multiple establishments, calculate rates separately for each establishment. A company-wide average can be useful internally, but OSHA recordkeeping and ITA filing are establishment-based.

Common mistakes

• Counting the same case twice. A case belongs in one case-classification bucket on the 300 log. Do not add days away plus restricted days as if they were separate cases.
• Using days instead of cases for DART. DART counts cases that involved days away, restriction, or transfer. The number of days is a different 300A field.
• Mixing company-wide hours with site-level cases. The numerator and denominator must cover the same establishment and same year.
• Treating a rate as a filing requirement. TRIR and DART are performance metrics. Whether you must electronically submit OSHA 300A depends on size, industry, and recordkeeping status. Use the filing checker for that question.

How RegFile uses these rates

RegFile reads your OSHA 300 log, builds the 300A summary, checks the case totals against the underlying rows, and preserves the evidence trail. TRIR and DART are useful review signals because they make obvious mismatches easier to spot before filing.

If your DART rate looks high because every recordable case was classified as days-away, restricted, or transferred, that classification can be correct. Treat it as a cue to review the log before anyone certifies the annual summary.

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This is informational, not legal advice - verify against your adopted rule.