How to Calculate Frequency Rate of Accidents

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Accident Frequency Rate Calculator

Enter the total number of recordable accidents in the period.
Total hours worked by all employees during the period.
1,000,000 (International / UK / AUS) 200,000 (OSHA / USA) Choose 1,000,000 for general AFR or 200,000 for OSHA Incident Rates.
Frequency Rate
0.00
function calculateSafetyRate() { // Get input values var accidentsInput = document.getElementById('numAccidents').value; var hoursInput = document.getElementById('totalHours').value; var standardMultiplier = document.getElementById('calcStandard').value; // Parse values var accidents = parseFloat(accidentsInput); var hours = parseFloat(hoursInput); var multiplier = parseFloat(standardMultiplier); // Validation if (isNaN(accidents) || accidents < 0) { alert("Please enter a valid number of accidents."); return; } if (isNaN(hours) || hours <= 0) { alert("Please enter a valid number of man-hours worked (must be greater than 0)."); return; } // Calculation: (Accidents * Multiplier) / Hours var frequencyRate = (accidents * multiplier) / hours; // Display Result var resultBox = document.getElementById('resultBox'); var rateResult = document.getElementById('rateResult'); var resultText = document.getElementById('resultText'); resultBox.style.display = 'block'; rateResult.innerText = frequencyRate.toFixed(2); // Interpretation Logic var standardName = (multiplier === 1000000) ? "million" : "200,000"; resultText.innerText = "This means there were " + frequencyRate.toFixed(2) + " accidents for every " + standardName + " hours worked."; }

How to Calculate Frequency Rate of Accidents

The Accident Frequency Rate (AFR) is a critical Key Performance Indicator (KPI) used by Health, Safety, and Environment (HSE) professionals to measure the safety performance of a workplace. Unlike a simple count of accidents, the frequency rate normalizes the data based on the number of hours worked, allowing companies to compare safety performance across different time periods or project sizes.

Formula: (Number of Accidents × K) / Total Man-Hours Worked

Understanding the Variables

  • Number of Accidents: Usually refers to Lost Time Injuries (LTI) or recordable incidents that occurred during the reporting period.
  • Total Man-Hours Worked: The sum of all actual hours worked by all employees (and often contractors) during the specific period. Do not include leave, sickness, or holidays.
  • Constant (K): This standardizes the rate.
    • 1,000,000: Commonly used internationally (UK, Australia, etc.) to represent the rate per million hours worked.
    • 200,000: Commonly used by OSHA in the United States to represent the equivalent of 100 full-time employees working for a year (100 employees × 40 hours × 50 weeks).

Example Calculation

Let's say a construction company wants to calculate its Lost Time Injury Frequency Rate (LTIFR) for the year using the international standard (1,000,000).

  • Accidents: 3 lost time injuries occurred.
  • Workforce: 250 employees working 40 hours a week for 50 weeks.
  • Total Hours: 250 × 40 × 50 = 500,000 man-hours.

Calculation: (3 × 1,000,000) / 500,000 = 6.0

This result of 6.0 means that for every one million hours of work performed, 6 lost time injuries are statistically likely to occur based on current performance.

Why is Accident Frequency Rate Important?

Tracking the AFR allows organizations to:

  1. Benchmark Performance: Compare current safety statistics against past years or industry averages.
  2. Identify Trends: A rising AFR indicates that existing safety controls may be failing or that complacency is setting in.
  3. Tender Requirements: Many clients require contractors to submit their AFR or LTIFR scores during the bidding process to ensure they are hiring safe companies.

Difference Between Frequency Rate and Severity Rate

While the Frequency Rate measures how often accidents happen, the Severity Rate measures how serious those accidents are (usually by tracking the number of days lost). A company might have a high frequency of minor accidents (high AFR) but very few days lost (low Severity Rate), or vice versa.

Tips to Lower Your Frequency Rate

  • Near Miss Reporting: Encourage reporting of near misses to fix hazards before they cause injuries.
  • Safety Training: Regular toolbox talks and induction training keep safety top of mind.
  • Risk Assessments: Regularly review and update risk assessments for changing site conditions.
  • Behavior-Based Safety: Observe and correct unsafe behaviors immediately.

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