Injury rates turn a count of injuries into a number you can compare, from year to year and with other companies. Each rate is the number of cases multiplied by 200,000, divided by the hours worked: injuries per 100 full-time workers in a year.
The formulas
- TRIF = (lost-time + modified work + medical treatment + fatal cases) × 200,000 ÷ hours worked
- LTIF = lost-time cases × 200,000 ÷ hours worked
- Disabling injury rate = (lost-time + modified work cases) × 200,000 ÷ hours worked
- Severity rate = days lost × 200,000 ÷ hours worked
A worked example: a contractor with 75 full-time workers works about 150,000 hours a year. With 1 lost-time case, 2 modified work cases and 1 medical treatment case, its TRIF is 4 × 200,000 ÷ 150,000 = 5.33, its LTIF is 1.33, and its disabling injury rate is 4.00.
What counts as recordable
A case is recordable when it needs more than first aid: medical treatment from a doctor, modified or restricted work, time off beyond the day of the injury, or a death. First aid only cases and near misses are not counted in these rates, but recording them is how you prevent the ones that are. Count each case once, at its most serious outcome: a case that starts as modified work and becomes lost time is a lost-time case.
Why your rates matter
Clients and prequalification programs ask contractors for their TRIF and lost-time rates, often for three to five years, before they award work. A COR audit looks at whether you track and review your injury statistics. And in Alberta, your claims history feeds your WCB premium and your Partnerships in Injury Reduction refunds.
For context, Alberta's lost-time claim rate was 1.35 and its disabling injury rate 2.42 per 100 person-years in 2024. See the Canadian workplace injury statistics for the national numbers and what causes most injuries.
Alberta rates: Government of Alberta, Workplace injury, illness and fatality statistics: provincial summary 2024. Per 100 person-years is the same base as 200,000 hours worked.