Incidence rate (TRIR)
Used on the ASP, CSP and CHST. The worked example below is computed by code and checked against the source.
IR = (N × 200,000) ÷ EH
N = recordable injuries and illnesses; EH = total hours worked by all employees in the year; 200,000 = 100 full-time workers × 40 h × 50 weeks.
Worked example
BLS example: 7 recordable cases and 400,000 hours worked.
(7 × 200,000) ÷ 400,000 = 3.5
The source prints this result, and our code reproduces it.
Run your own numbers: OSHA incident rate calculator.
Where it appears on the exam
ASP: ASP11 Domain 1, Mathematical Calculations
Blueprint: ASP11 Domain 1, task 8: lagging indicators (incidence rates)
Practice: Safety Math: Incident Rates, Noise Dose, Slopes, Lifting, OSHA Recordkeeping and Reporting
CSP: CSP11 Domain 2, Program Management
Blueprint: CSP11 Domain 2, task 7: leading and lagging indicators
Practice: Incident and DART Rate Calculations
CHST: CHST5 Domain 3, Safety Program Development, Implementation, and Sustainment
Blueprint: CHST5 Domain 3, skill 3: trends related to incidents and accidents
Practice: Incident Rate Calculations
Source
The formula comes from
BLS, How To Compute Your Firm's Incidence Rate for Safety Management(opens bls.gov in a new tab)“(Number of injuries and illnesses X 200,000) / Employee hours worked = Incidence rate (The 200,000 hours in the formula represents the equivalent of 100 employees working 40 hours per week, 50 weeks per year, and provides the standard base for the incidence rates.)”
Questions
- What is the formula for incidence rate (TRIR)?
- IR = (N × 200,000) ÷ EH. N = recordable injuries and illnesses; EH = total hours worked by all employees in the year; 200,000 = 100 full-time workers × 40 h × 50 weeks.
- Will this formula be given on the BCSP exam?
- BCSP says the formula is included in the question whenever one is needed, unless the question is testing whether you know the formula. You can't bring a formula sheet into the exam, so learn what each formula does and when to use it.
BCSP on formulas at the exam
BCSP, What to Expect When Sitting for a BCSP Exam (item 7)(opens bcsp.org in a new tab)“For any question requiring a mathematical formula, the formula will be included within the exam question (unless the question is specifically testing your knowledge of a formula). You will not be provided or permitted to bring a formula sheet.”
Related
- Recordable injury or illness
- Lagging indicator
- DART rate
- ASP formula sheet
- CSP formula sheet
- CHST formula sheet
Checked 2026-10-16. Spot a problem? Email hello@passcited.com.