An OSHA incident rate calculator turns two numbers, your count of recordable injuries and the total hours your team worked, into TRIR: the Total Recordable Incident Rate. The formula is (recordable cases × 200,000) ÷ hours worked. That single score lets a five-person shop and a five-thousand-person plant compare safety on the same scale, which is why OSHA, insurers, and prequalification systems all ask for it.
Below you will find the exact math, a worked example, what counts as a recordable case, and how to tell whether your result is any good. You can run your own figures first and read the explanation second.
The TRIR formula and why it uses 200,000 hours
TRIR (Total Recordable Incident Rate) measures how many OSHA recordable injuries and illnesses a workplace logs per 100 full-time workers in a year. Here is the formula:
- TRIR = (recordable cases × 200,000) ÷ total hours worked
The 200,000 is not arbitrary. It is what 100 full-time employees work in a year: 100 people × 40 hours a week × 50 weeks. Dividing by your actual hours and scaling back to that baseline gives a per-100-worker figure, so headcount stops distorting the comparison. A busy warehouse and a quiet office get judged on the same yardstick.
Estimate yours with the interactive tool below. Switch the reporting convention to US OSHA and it returns TRIR and DART from your case counts and hours.
Accident Incident Rate Calculator UK
Work out every workplace safety rate that matters in Great Britain from one set of numbers: AFR per 100,000 hours, LTIFR per 1,000,000 hours, and the HSE incidence rate per 100,000 employees, benchmarked against the latest published GB figures. Flip one switch to see the same data in US OSHA terms (TRIR, DART) for group reporting.
Formulae follow the conventions HSE and OSHA publish: AFR = LTIs × 100,000 ÷ hours; LTIFR = LTIs × 1,000,000 ÷ hours; HSE incidence = injuries × 100,000 ÷ average employed; TRIR/DART = cases × 200,000 ÷ hours. GB benchmarks are from the HSE 2024/25 annual statistics (59,219 RIDDOR-reported employee injuries, 209 per 100,000 employees; 680,000 self-reported injuries, 2,070 per 100,000 workers; 124 worker fatalities, 0.37 per 100,000). HSE cautions that employers report only around half of RIDDOR-qualifying injuries, so cross-sector comparisons carry uncertainty. This tool does not determine what you must report under RIDDOR and is not legal advice; reporting duties are set out at hse.gov.uk/riddor.
The embedded module is the accident incident rate calculator, which handles both the US metrics and the UK equivalents from one set of inputs.
How to calculate your DART rate
DART stands for Days Away, Restricted, or Transferred. It counts only the serious cases: an injury that kept someone off work, on light duty, or moved to another job. The math mirrors TRIR:
- DART = (DART cases × 200,000) ÷ total hours worked
Because DART cases are a subset of your recordables, this number is always equal to or below your TRIR. If they match, every recordable you logged was serious enough to pull a worker off the line, which is worth a second look. On the OSHA 300 log, DART cases are the ones marked in columns H (days away) and I (job transfer or restriction).
Worked example: a 200-person site
Say a distribution center employs 200 people who together clocked 352,000 hours last year. The OSHA 300 log shows 6 recordable cases, and 3 of those involved days away or restricted duty.
- TRIR: (6 × 200,000) ÷ 352,000 = 1,200,000 ÷ 352,000 = 3.41
- DART: (3 × 200,000) ÷ 352,000 = 600,000 ÷ 352,000 = 1.70
So this site records 3.41 recordable cases and 1.70 days-away cases per 100 workers per year. Round to two decimals, the way most reports and prequalification portals expect. Change any input and the numbers move: cut recordables to 3 and the score drops to 1.70. That is the whole point of the metric, it responds to real reductions, not to how big you are.
What counts as an OSHA recordable case
Your score is only as honest as your case count, so the recordability test matters. Under 29 CFR 1904, a work-related injury or illness is recordable if it results in any of these:
- Death
- Days away from work
- Restricted work or transfer to another job
- Medical treatment beyond first aid
- Loss of consciousness
- A significant injury or illness diagnosed by a physician (for example a fractured bone or a punctured eardrum)
First aid alone does not make a case recordable. Bandages, over-the-counter medicine at nonprescription strength, and a tetanus shot are first aid. Stitches, prescription drugs, and physical therapy cross the line into recordable. Getting this boundary right is where most miscounts happen, and a single misclassified case can swing a small employer’s TRIR by a full point.
Practitioner note: keep a short written rationale next to each 300 log entry explaining why you did or did not record it. When an auditor or a client asks two years later, that one line saves an afternoon of digging.
What is a good incident rate?
Lower is better and zero is the target, but context sets the bar. The Bureau of Labor Statistics (BLS) publishes an annual private-industry average that hovers near 2.7 recordable cases per 100 full-time workers. As a rough guide:
- Under 1.0: strong, better than most industries
- Around 2.5 to 3.0: near the national all-industry average
- Above 4 or 5: elevated, worth a hard look at your hazards
Those bands are blunt, though. A number that looks high for an office is normal for construction or nursing homes, which run well above the all-industry line. Always benchmark against your own NAICS code using the BLS industry tables, not the headline figure. A roofing contractor at 4.0 may be beating its sector; a law firm at 4.0 has a real problem.
One more caution: a very low score can mean a genuinely safe operation, or it can mean underreporting. Insurers and OSHA look at the trend and at your DART share, not just the single headline value.
TRIR, DART, and the other safety numbers
Several metrics come off the same 300 log. Here is how the common ones line up:
| Metric | Counts | Base hours | Formula |
|---|---|---|---|
| TRIR | All recordable cases | 200,000 | cases × 200,000 ÷ hours |
| DART | Days away, restricted, transferred | 200,000 | DART cases × 200,000 ÷ hours |
| DAFWII | Days-away cases only | 200,000 | days-away cases × 200,000 ÷ hours |
| LTIFR | Lost-time injuries | 1,000,000 | lost-time cases × 1,000,000 ÷ hours |
The first three share the 200,000-hour base, so they are directly comparable. LTIFR, common outside the US, uses a million-hour base, which is why you cannot compare a UK frequency figure to a US TRIR without converting first. If a workplace injury later turns into a claim, our guide to average settlements by injury type covers what comes next on the compensation side.
The UK equivalent: accident frequency rate
British employers report to the HSE, not OSHA, and use the Accident Frequency Rate (AFR): lost-time injuries × 100,000 ÷ hours worked. Because AFR uses a 100,000-hour base rather than 200,000, a UK figure is roughly half its US counterpart for the same events, so never compare them raw. The tool above flips between both conventions from one set of inputs, which is handy for multinational groups that report US TRIR to head office and AFR to a British regulator.
Run your numbers before your next report
You now have the whole method: TRIR and DART both scale your case count to 200,000 hours so any size of workforce lands on one comparable score, and the BLS industry tables tell you whether that score is good. Rather than build the formula in a spreadsheet each quarter, drop your recordable count and payroll hours into the OSHA incident rate calculator above, switch it to the US convention, and get TRIR, DART, and the severity figure in one pass. Keep the trend line, not just this year’s value, and you will spot problems while they are still small.
Frequently asked questions
What is the OSHA incident rate formula?
TRIR equals your recordable cases multiplied by 200,000, divided by total hours worked in the year. DART uses the same math but counts only cases with days away, restriction, or transfer. The 200,000 figure represents 100 full-time employees working 40 hours a week for 50 weeks.
What is a good TRIR score?
Lower is better, and zero is the goal. The private-industry average sits near 2.7 recordable cases per 100 workers, per BLS data, so many employers treat anything under 3.0 as acceptable and under 1.0 as strong. Compare against your own NAICS industry code rather than the all-industry number.
What is the difference between TRIR and DART?
TRIR counts every OSHA recordable case. DART counts only the more serious ones that kept a worker away from the job, on restricted duty, or transferred. DART is always equal to or lower because it is a subset of the same recordable log.
How do I calculate hours worked for the formula?
Add up actual hours all employees worked during the year, including overtime, from payroll records. Exclude vacation, sick leave, and holidays. Do not estimate 2,080 hours per worker if you have real payroll totals, since that overstates the denominator and understates your score.
Do small businesses have to calculate an incident rate?
Employers with 10 or fewer workers, and those in certain low-hazard industries, are partially exempt from OSHA recordkeeping. Larger firms keep the 300 log and often compute TRIR anyway because clients, insurers, and prequalification systems ask for it.