TRIR & DART Safety Rate Calculator

How this is calculated

OSHA incident rates put every workplace on the same footing by scaling recordable cases to a fixed number of hours. The standard basis is 200,000 hours, which is 100 full-time workers putting in 40 hours a week for 50 weeks a year. That is why a TRIR reads naturally as cases per 100 full-time workers per year.

TRIR counts every OSHA recordable case. The DART rate is a subset, counting only cases serious enough to involve days away from work, restricted duty, or a job transfer, so DART is always less than or equal to TRIR. Both use the same 200,000-hour basis.

How to read these numbers

• Cases per 100 workers per year. A TRIR of 3.0 means that, at your current pace, about three recordable cases would occur for every 100 full-time workers over a year.
• Hours worked, not headcount. The denominator is actual hours worked, including overtime, not a simple employee count. Use payroll hours for accuracy; the optional employee field here is only a sanity check.
• Recordability follows OSHA rules. What counts as recordable and as DART is defined by OSHA regulation. This tool does the arithmetic; it does not decide whether a given case is recordable.
• Context matters. Compare against your industry's published averages, and remember that low case counts make small changes swing the rate a lot.

This is educational content to help you compute standard safety metrics. For how a connected operation surfaces the leading indicators behind these numbers, read the CLS case study.