TRIR and DART Rate Calculator

Turns your headcount, hours worked and OSHA recordable cases into TRIR, DART and lost-time incident rates for safety managers and small operations teams.

Your estimate

Total hours worked...

Total recordable incident rate (TRIR)...

DART rate...

Lost-time incident rate (LTIR)...

Estimates only. Assumptions are listed below, and you can change every input.

Insurers, prospective clients and auditors ask for your TRIR and DART rate, and calculating them by hand from a spreadsheet of hours and OSHA 300 entries is easy to get wrong. A misplaced decimal or a wrong hours total can make a safe site look risky, or hide a real problem until an inspection finds it.

The calculator builds your total worked hours from headcount and average hours per employee, then applies the standard OSHA formula: cases multiplied by 200,000, divided by hours worked. It does not compare you to an industry average, because that depends on your NAICS code and the latest Bureau of Labor Statistics table, which you should look up separately.

How to use this tool

Enter your average headcount for the period and the average hours each person actually worked.
Copy the case counts from your OSHA 300 log: total recordables, cases with days away, restricted or transferred, and lost-time cases.
Read the TRIR, DART and LTIR results and compare them against the published rate for your NAICS code or against your own prior years.

What the math assumes

Uses the OSHA convention of a 200,000 hour base, which represents 100 full-time workers at 40 hours a week for 50 weeks.
Total hours are estimated as headcount multiplied by average hours per employee; if you have actual payroll hours for the period, divide that total by your headcount and enter the result, rounded to the nearest hour, as the average.
Only cases that meet OSHA recordkeeping criteria should be counted; first aid only cases are excluded.
DART cases and lost-time cases are treated as subsets of recordable cases, so they should never exceed the recordable total.
The tool reports your own rates only and does not include industry averages, which vary by NAICS code and year.

Frequently asked questions

Why does the calculator use 200,000 hours instead of my actual hours?

Your actual hours are used as the divisor. The 200,000 figure is the multiplier OSHA uses so that rates from a 20 person shop and a 2,000 person plant can be compared as if each had 100 full-time workers.

Should I count near misses and first aid cases in the recordable total?

No. Only cases that meet OSHA recordkeeping criteria, such as medical treatment beyond first aid, restricted work, days away or loss of consciousness, belong in the recordable count. Near misses and first aid cases are worth logging, but in a separate register.

Can I calculate a quarterly TRIR with this tool?

Yes. Enter the hours actually worked during the quarter and the cases recorded in that quarter. The result is annualized automatically by the 200,000 hour base, so a small period with one case will show a high rate.

Link to this toolhttps://safetypingr.com/tools/trir-dart-rate-calculator/

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