Frequency Rate and Severity Rate Calculator – Cost Calculator

Workplace Safety: Frequency Rate & Severity Rate Calculator

Standardized calculation based on 200,000 worker hours (equivalent to 100 FT employees).

Number of Recordable Incidents (Accidents):

Total Number of Lost Workdays:

Total Employee Hours Worked (in period):

Calculation Results

Frequency Rate (FR): (Incidents per 100 full-time workers)

Severity Rate (SR): (Lost days per 100 full-time workers)

function calculateSafetyRates() { // Get input values var incidentsStr = document.getElementById("numIncidents").value; var lostDaysStr = document.getElementById("totalLostDays").value; var totalHoursStr = document.getElementById("totalHoursWorked").value; // Parse to floats var incidents = parseFloat(incidentsStr); var lostDays = parseFloat(lostDaysStr); var totalHours = parseFloat(totalHoursStr); var resultsDiv = document.getElementById("resultsArea"); // Validation: Check if values are numbers and totalHours > 0 if (isNaN(incidents) || isNaN(lostDays) || isNaN(totalHours) || totalHours <= 0 || incidents < 0 || lostDays < 0) { alert("Please enter valid, non-negative numbers for incidents and lost days, and a value greater than zero for total hours worked."); resultsDiv.style.display = "none"; return; } // Constant used for standardizing rates to 100 full-time employees working 40 hours/week for 50 weeks. var standardHoursConstant = 200000; // Calculate Frequency Rate // Formula: (Number of Incidents * 200,000) / Total Hours Worked var frequencyRate = (incidents * standardHoursConstant) / totalHours; // Calculate Severity Rate // Formula: (Total Lost Workdays * 200,000) / Total Hours Worked var severityRate = (lostDays * standardHoursConstant) / totalHours; // Display results rounded to 2 decimal places document.getElementById("frResult").innerHTML = frequencyRate.toFixed(2); document.getElementById("srResult").innerHTML = severityRate.toFixed(2); // Show results area resultsDiv.style.display = "block"; }

Understanding Workplace Safety Metrics: Frequency and Severity Rates

In the realm of occupational health and safety, measuring performance is crucial for identifying risks and implementing effective preventative measures. Two of the most critical standardized metrics used globally, particularly suited for OSHA compliance benchmarks, are the Frequency Rate and the Severity Rate. These key performance indicators (KPIs) allow companies of different sizes to compare their safety records accurately.

What is the Frequency Rate (FR)?

The Frequency Rate measures the number of recordable accidents or incidents that occur over a specific period, standardized to a common baseline. It answers the question: "How often do accidents happen?"

The standard formula used by this calculator is based on the OSHA benchmark of 200,000 hours, which represents 100 full-time employees working 40 hours per week for 50 weeks a year.

The Formula:
Frequency Rate = (Number of Recordable Incidents × 200,000) / Total Employee Hours Worked

For example, if a company had 5 recordable incidents and 450,000 total hours worked in a year, the Frequency Rate would be (5 × 200,000) / 450,000 = 2.22. This means that for every 100 full-time employees, there were 2.22 incidents.

What is the Severity Rate (SR)?

While the Frequency Rate tells you how often accidents happen, it doesn't indicate how serious they are. The Severity Rate addresses this by measuring the amount of time lost due to those work-related injuries or illnesses. It answers the question: "How serious is the impact of accidents on workforce availability?"

Like the Frequency Rate, this is standardized using the 200,000-hour constant to allow for fair comparison regardless of company size.

The Formula:
Severity Rate = (Total Number of Lost Workdays × 200,000) / Total Employee Hours Worked

Continuing the example above, if those 5 incidents resulted in a combined total of 35 lost workdays, the Severity Rate would be (35 × 200,000) / 450,000 = 15.56. This means for every 100 full-time employees, 15.56 days of work were lost due to injury.

Interpreting the Results

High Frequency, Low Severity: Indicates a workplace where minor accidents happen frequently. This often points to issues with housekeeping, training, or minor procedure adherence.
Low Frequency, High Severity: Accidents are rare, but when they occur, they are catastrophic. This may indicate major risks in high-hazard operations that are generally well-controlled but disastrous if a control fails.
High Frequency, High Severity: The most alarming scenario, indicating significant systemic failures in safety management requiring immediate, comprehensive intervention.

By regularly tracking these metrics using this calculator, safety managers can identify trends, benchmark against industry averages, and prioritize resources to reduce both the number of accidents and their impact on the workforce.