OSHA Severity Rate Calculator
Calculate the average severity of workplace injuries based on lost workdays.
How to Calculate OSHA Severity Rate
Understanding workplace safety metrics is crucial for maintaining a compliant and safe environment for employees. The OSHA Severity Rate (often referred to as the Lost Time Case Rate or simply Severity Rate) is a quantitative measure that helps safety managers understand how serious the injuries occurring in their workplace are.
While the Recordable Incident Rate (TRIR) tells you how often injuries happen, the Severity Rate tells you how severe those injuries are by tracking the number of days lost.
The OSHA Severity Rate Formula
To calculate the severity rate, OSHA uses a standardized formula that normalizes data per 100 full-time employees per year. This allows companies of different sizes to compare their safety performance accurately.
Here is a breakdown of the variables:
- Total Lost Workdays: The sum of all days employees spent away from work or on restricted duty due to work-related injuries or illnesses.
- Total Employee Hours Worked: The actual total hours worked by all employees (full-time, part-time, seasonal) during the reporting period. Do not include vacation, sick leave, or holidays.
- 200,000: This constant represents the equivalent of 100 employees working 40 hours per week for 50 weeks a year (100 × 40 × 50 = 200,000).
Step-by-Step Calculation Example
Let's look at a realistic scenario for a manufacturing plant to understand how the calculator works manually.
Scenario: ABC Manufacturing has 150 employees. Over the course of the year:
- They experienced 3 incidents resulting in time away from work.
- Incident 1 resulted in 5 lost days.
- Incident 2 resulted in 12 lost days.
- Incident 3 resulted in 3 lost days.
- Total Lost Workdays = 20 (5 + 12 + 3).
- Total hours worked by all employees was 310,000 hours.
The Math:
- Multiply Lost Workdays by 200,000:
20 × 200,000 = 4,000,000 - Divide by Total Hours Worked:
4,000,000 / 310,000 = 12.90
The Severity Rate is 12.90. This means that for every 100 full-time employees, approximately 13 days of productivity were lost due to injuries.
Why Monitor Severity Rate?
Tracking this metric provides deeper insights than simple accident counts:
- Financial Impact: Lost days directly correlate to lost productivity and higher worker's compensation costs.
- Risk Assessment: It helps identify if specific departments are prone to more dangerous accidents requiring longer recovery times.
- Benchmarking: You can compare your severity rate against industry averages provided by the Bureau of Labor Statistics (BLS).
What Counts as a "Lost Workday"?
According to OSHA guidelines, you must count the number of calendar days the employee was unable to work as a result of the injury or illness, regardless of whether the employee was scheduled to work on those days. Weekend days, holidays, vacation days, or other days off are included in the total number of days recorded if the employee would not have been able to work due to the injury.
Note: The count of days begins on the day after the injury occurred.
Frequently Asked Questions
Does Severity Rate include restricted duty?
Usually, the standard Severity Rate focuses on "Days Away from Work." However, some organizations calculate a DART rate (Days Away, Restricted, or Transferred) which includes days where an employee is at work but cannot perform their routine job functions.
What is a "good" Severity Rate?
A "good" rate varies heavily by industry. Construction and manufacturing will naturally have higher rates than finance or retail. The best way to determine if your rate is good is to compare it to your specific NAICS code average from the Bureau of Labor Statistics.
Why do we use 200,000 instead of 1,000,000?
The 200,000 figure is the OSHA standard for annualizing data for 100 employees. Some industries (like mining via MSHA) might use 1,000,000 man-hours, but for general industry OSHA compliance, 200,000 is the required multiplier.