Free tools / OSHA Rate Calculator
TRIR + DART + Form 300A — calculate it in 30 seconds.
Every U.S. employer that records OSHA-recordable injuries calculates the same five rates at year-end. They show up on insurance premiums (mod-rate adjustments lean on TRIR), in contract-bid prequalification questionnaires, on BLS injury-survey responses, and on the Form 300A you post on the wall between February and April. The formulas are standardised — case count × 200,000 / annual hours worked — but the bookkeeping (which cases count, which days count, what's an OR-only) confuses every first-year safety hire. This calculator does the math once you have the counts.
Why this matters
One wrong number ripples into insurance, contracts, and the wall.
TRIR is the number your insurance broker quotes when they push back on your premium. A miscount of one recordable case can move TRIR by 0.5 on a small employer, which shows up as four figures on the next workers' comp renewal. DART has similar weight in pre-qualification questionnaires for general-contractor work — a DART of 1.8 vs 2.0 is the difference between getting on the bid list and not getting an RFP.
The Form 300A you post on the wall between February and April carries the same numbers but in the BLS-survey-compatible shape: cases by category (skin / respiratory / poisoning / hearing loss / all other illnesses) plus the totals (death / days away / restricted / other recordable / total days). Getting the totals wrong on the posting is its own OSHA citation (1904.32(b)(5), 1904.32(b)(6)). And the BLS Survey of Occupational Injuries and Illnesses (SOII) sample your firm into pulls the same numbers a different way.
None of this is hard math. It's standardised, the formulas haven't changed since 1971. But every standard rate uses a denominator of 100 full-time workers × 50 weeks × 40 hours = 200,000 employee-hours — multiplied through to your case count and divided by your actual hours worked. Easy to get the multiplication backwards. This calculator does it once.
The five rates
What the calculator computes.
- TRIR — Total Recordable Incident Rate
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(total recordable cases × 200,000) / annual hours worked
The headline rate. Every recordable case on your Form 300 counts — death, days away, restricted, transfer, medical-treatment-only. The most-quoted EHS metric on the planet. - DART — Days Away, Restricted, or Transferred
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((DAFW + DJTR) × 200,000) / annual hours worked
Filters out the medical-treatment-only cases that don't drive a workforce-impact metric. The pre-qualification questionnaires lean on this one. - DAFW — Days Away From Work Rate
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(days-away cases × 200,000) / annual hours worked
The lost-time component of DART. Drill-down on workers'-comp impact. - Severity Rate (lost-day rate)
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(total days lost × 200,000) / annual hours worked
Distinguishes "one case, 90 days off" from "ten cases, 9 days off each" — same DAFW, very different severity. - Fatality Incidence Rate
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(fatalities × 200,000) / annual hours worked
Usually zero — but when it isn't, the per-200k-hour rate is the comparable metric across employer sizes.
Common gotchas
The bookkeeping that bites people.
- One case, multiple outcomes. If a case has both days away AND restricted days, it counts ONCE in the DAFW total + ONCE in the DJTR total. Don't double-count it in DART.
- Annual hours include overtime + part-time. Use actual hours worked from payroll, not a 2,080-hour-per-FTE estimate. Overtime + leased-employee hours count if those workers reported to your supervisor.
- Multi-establishment employers compute rates per establishment. Each Form 300A covers one establishment. The federal-wide-firm rate is a separate roll-up that BLS computes; you don't post one on the wall.
- OSHA's day-count caps at 180. No matter how long the case keeps the worker off, only the first 180 days count toward the 300A totals + severity rate. The case still counts as 1 DAFW case until the worker returns or reaches MMI.
- The 200,000 constant doesn't change. Even though the modern full-time year is closer to 2,000 hours, OSHA's rate denominator is fixed at 200,000 = 100 workers × 50 weeks × 40 hours. The shape lets you compare your 12-worker shop to a 50,000-worker manufacturer apples-to-apples.
Calculate your rates step by step.
The calculator takes the same numbers your Form 300A asks for — total recordable cases, cases with days away, restricted/transfer cases, fatalities, total days lost, annual hours worked, and average employee count — and produces all five OSHA rates plus a 300A-shaped summary you can copy to clipboard.
SE keeps a running rate calculation against every recordable incident your team files — TRIR + DART + severity rate + fatality rate update on the dashboard the moment a case is classified Recordable, and the Form 300A renders directly from the same numbers at year-end. The free calculator above is the one-shot version of that math; the platform makes it continuous.
Three related free tools: Is this case recordable? (the 1904.7 cascade that decides which cases enter the count); Where do I report this? (which regulator covers your establishment); and EPCRA Tier II checker (does your chemical inventory trigger the annual Tier II filing?).