Free tool
OSHA incident rate calculator.
Work out TRIR, DART, lost time incident rate and severity rate from your hours worked and case counts. Everything runs in your browser, nothing is stored or sent anywhere.
How the three rates compare
The formula
Every OSHA rate uses the same shape. Count the cases, multiply by 200,000, divide by hours worked:
TRIR = (recordable cases × 200,000) / total hours worked
The 200,000 is 100 full-time employees working 40 hours a week for 50 weeks. It is there so a 40-person yard and a 4,000-person terminal network can be compared on the same scale. Swap the case count and you get the other rates: DART cases give you the DART rate, days away give you the severity rate.
TRIR and DART are not the same number
TRIR counts every case on your OSHA 300 log. DART counts only the ones where someone actually lost time, went on restricted duty, or was moved to another job. DART is always the smaller number. If your calculator shows DART above TRIR, the case counts are miscategorised.
Severity rate is the one people skip, and it is the one that tells you whether you have a lot of small cuts or a few serious injuries. Two sites can post the same TRIR while one of them is quietly far more dangerous.
Getting the hours right
Hours worked means hours actually on the clock. Take out vacation, sick leave and holidays. Include overtime, and include temporary or contract workers if you supervise their day-to-day work. Overstating hours quietly flatters every rate on this page.
What counts as recordable
A case goes on the 300 log when it involves medical treatment beyond first aid, days away, restricted duty, job transfer, loss of consciousness, or a significant diagnosis from a licensed provider. OSHA publishes the full recordkeeping rule under 29 CFR 1904, and the Bureau of Labor Statistics publishes incidence rates by industry code so you can see where your number sits against comparable operations.
Your rate is only as honest as your reporting
This is the part the arithmetic cannot fix. The calculation assumes your case count is complete. In heavy industry it usually is not. A near miss on the quay goes out over the radio. A pinched hand gets mentioned in a shift handover and never reaches a form. A contractor incident lives in a WhatsApp thread the safety manager was never in.
Those cases still happened. They just never reached the log, which means your TRIR looks better than your operation actually is, and the pattern that would have predicted the serious one stays invisible.
