How TRIR is calculated
Multiply the total recordable case count by 200,000, then divide by employee hours worked. TRIR is a rate, not a percentage.
The base represents 100 full-time equivalent workers working 40 hours per week for 50 weeks. Keep cases and hours aligned to the same workforce and period. See OSHA’s explanation of the incidence-rate method.
Before entering your figures
- Use the applicable OSHA recordkeeping rules to establish which cases are recordable. Do not count every first-aid event or near miss.
- Enter actual employee hours worked, including overtime worked. Exclude paid time not worked, such as vacation or sick leave. Check the OSHA forms and hours-worked worksheet for the reporting scope.
- Zero cases is a valid input. Hours must be greater than zero.
A worked example
For 3 recordable cases over 250,000 hours worked:
(3 × 200,000) ÷ 250,000 = 2.40
These are illustrative figures, not an industry benchmark.
Put the rate in context
Compare similar operations and periods. A single case can cause large changes for a small workforce. OSHA advises considering multiple indicators when evaluating safety performance. A low rate alone does not show that hazards are controlled.
This tool uses the US 200,000-hour method. It is not a UK RIDDOR calculator or a million-hour frequency-rate calculator. Arithmetic is tested for this prototype; independent professional review remains a release requirement.
Common questions after calculating TRIR
Is my TRIR good or bad?
There is no universal pass/fail number. A suitable benchmark needs the same metric and a comparable sector, size and period. Below a reference does not prove your hazards are controlled.
How can we improve the result?
Prevent recordable injuries by identifying and controlling their causes. Review incidents, prioritise effective controls and verify corrective actions. Keep records accurate; do not discourage reporting or alter valid cases to lower the number.
What if we do not know the hours worked?
Use actual records where available. If they are unavailable, follow the estimation worksheet in OSHA Form 300A instructions and document your assumptions. Headcount alone is not hours worked.
Is TRIR a percentage?
No. It is a case rate normalized to 200,000 hours. Do not add a percentage sign.
Can I use monthly or year-to-date figures?
Use matching cases and hours for that period and keep the 200,000 constant. Label the period. Short periods can be volatile and should not be compared uncritically with full-year figures.
Does zero TRIR prove that a workplace is safe?
No. Zero recordable cases gives a rate of zero when hours are positive. That describes the entered records, not the absence of hazards.
Are TRIR and DART interchangeable?
No. DART uses cases involving days away, restricted work or job transfer. Do not substitute that count for the total recordable case count.
Original references
- OSHA: clarification of the incidence-rate formula — 23 August 2016. Formula, fixed base and interpretation limitations.
- OSHA recordkeeping forms and instructions — case counts and employee hours.
- OSHA recordkeeping requirements — rules, forms and guidance.
Formula reference checked 1 November 2026. HSECalc is independent and is not endorsed by OSHA.