Frequency Rate (FR) – Complete Guide for Safety Professionals
Workplace safety performance is measured through different indicators that help organizations evaluate how well they are protecting their employees. Among these indicators, the Frequency Rate (FR) is one of the most widely used.
Frequency Rate (FR) is a standard safety KPI (Key Performance Indicator) used across industries to identify how often workplace injuries occur in relation to the total manhours worked. It allows companies of all sizes to compare accident data fairly, even if their workforce strength or project duration is different.
In this guide, we’ll cover everything you need to know about Frequency Rate (FR): definition, formula, calculation, significance, limitations, comparison with other safety indicators, case studies, FAQs, and practical applications.
🔹 What is Frequency Rate (FR)?
Frequency Rate (FR) is a metric used to calculate the number of injuries per 1,000,000 manhours worked. It helps organizations standardize accident frequency for comparison across projects, industries, and even countries.
👉 In simple words:
FR shows how often accidents happen in the workplace when normalized against one million hours worked.
- ILO Definition: According to the International Labour Organization (ILO), frequency rate represents the number of disabling injuries per 1,000,000 hours worked.
- Industry Use: FR is used in construction, oil & gas, manufacturing, mining, and government safety audits.
🔹 Formula for Frequency Rate (FR)
Here’s the standard formula:
FR = (Number of Injuries × 1,000,000) ÷ Total Manhours Worked
Where:
- Number of Injuries = The total number of recordable injuries (varies depending on company reporting rules).
- Total Manhours Worked = Combined hours of employees, contractors, and sometimes inducted visitors.
- 1,000,000 = Normalization constant used by the ILO for global comparison.
🔹 Why 1,000,000?
You might wonder, why is 1,000,000 hours used as a benchmark?
The ILO selected 1,000,000 hours to standardize safety performance across companies of different sizes and avoid using very small decimal numbers.
- A full-time worker works around 2,000 hours/year (40 hrs/week × 50 weeks).
- For 500 workers, that equals:
500 × 2,000 = 1,000,000 hours
👉 Therefore, FR answers:
“How many injuries would occur if 500 full-time employees worked for one year?”
🔹 Example of Frequency Rate (FR) Calculation
Example 1:
- Total manhours worked = 500,000
- Number of injuries = 2
FR = (2 × 1,000,000) ÷ 500,000
FR = 4.0
✅ This means 4 injuries per 1 million hours worked.
Example 2:
- Total manhours worked = 2,000,000
- Number of injuries = 10
FR = (10 × 1,000,000) ÷ 2,000,000
FR = 5.0
✅ This means the project experienced a frequency rate of 5.0.
🔹 Importance of Frequency Rate (FR)
- Performance Measurement – Helps track how often workplace accidents occur.
- Comparison Across Sites – Standardizes accident reporting for small and large projects.
- Regulatory Compliance – Many clients and government agencies require FR in monthly/annual reports.
- Benchmarking – FR can be compared with industry averages or past years to evaluate improvements.
- Motivational Tool – Organizations often display FR on safety boards to encourage safe behavior.
🔹 FR in Different Industries
- Construction: Used to evaluate contractors and subcontractors.
- Oil & Gas: Reported as part of IOGP (International Association of Oil & Gas Producers) global safety statistics.
- Manufacturing: FR is monitored to ensure production safety and compliance with ISO 45001.
- Government: National safety authorities require FR for auditing and enforcement.
🔹 Limitations of Frequency Rate (FR)
While FR is useful, it has some limitations:
- Does Not Show Severity: A small cut and a broken leg both count as one injury.
- Lagging Indicator: It shows past performance, not predictive risk.
- Reporting Variations: Some organizations only count Lost Time Injuries (LTI), while others include all recordables.
- Impact of Small Numbers: In small projects, even one injury can make FR very high.
🔹 FR vs SR vs IR vs AFR
| Metric | Formula | Focus | Multiplier | Standard |
|---|---|---|---|---|
| FR (ILO) | (Injuries × 1,000,000) ÷ Manhours | Frequency of injuries | 1,000,000 hrs (~500 workers/year) | ILO / International |
| SR (ILO) | (Lost Days × 1,000,000) ÷ Manhours | Severity of accidents | 1,000,000 hrs | ILO / International |
| IR (OSHA) | (Recordable Cases × 200,000) ÷ Hours | Recordable injuries per 100 workers/year | 200,000 hrs | OSHA / U.S. |
| AFR (ILO) | (LTIs × 1,000,000) ÷ Hours | LTI frequency | 1,000,000 hrs | ILO / Global |
👉 Summary:
- FR = How often injuries occur.
- SR = How serious injuries are.
- IR = OSHA’s U.S. standard (200,000 hrs).
- AFR = ILO’s version of LTI frequency.
🔹 Factors Affecting Frequency Rate
- Workforce size – Small projects can show distorted FR.
- Industry type – Hazardous industries have higher FR.
- Safety culture – Strong safety culture = lower FR.
- Training & awareness – Regular toolbox talks reduce incidents.
- Leadership – Management commitment is crucial.
🔹 How to Reduce Frequency Rate
- Carry out proper risk assessments.
- Conduct regular safety training.
- Ensure strict PPE compliance.
- Implement Permit-to-Work (PTW) systems.
- Encourage near-miss reporting to prevent incidents.
- Perform audits and inspections regularly.
- Strengthen incident investigation systems.
🔹 Frequency Rate in Safety Reports
- Monthly Site Safety Reports: FR is a mandatory KPI.
- Annual HSE Reports: Used for public and client reporting.
- Safety Boards at Site: “1 Million Safe Manhours” milestones are often displayed.
- Client Audits: Contractors must report FR to qualify for projects.
🔹 Case Study Example
A construction project employed 2,000 workers with 5 million total manhours in one year. During this period:
- Total injuries = 15
- Lost days = 300
Calculations:
FR = (15 × 1,000,000) ÷ 5,000,000 = 3.0
SR = (300 × 1,000,000) ÷ 5,000,000 = 60.0
👉 Interpretation:
- FR = 3.0 (3 injuries per 1 million hours worked).
- SR = 60.0 (60 days lost per 1 million hours worked).
🔹 FAQs on Frequency Rate (FR)
Q1. Is Frequency Rate mandatory?
Yes, in most industries FR is required for monthly/annual safety reporting.
Q2. Does FR include First Aid cases?
Depends on policy. Some use FR for LTIs only, others include all recordables.
Q3. What is a good Frequency Rate?
Lower is better. Zero FR means no injuries in the reporting period.
Q4. Why does OSHA not use FR?
OSHA uses Incident Rate (IR) with a 200,000-hour base, while ILO uses FR with 1,000,000-hour base.
Q5. Can visitors’ hours be included in FR?
Yes, if they are inducted and exposed to site hazards.
🔹 Conclusion
Frequency Rate (FR) is one of the most important safety KPIs used globally to evaluate accident frequency. By normalizing injuries per 1,000,000 hours worked, it enables fair comparison across industries and projects.
While FR has limitations (it doesn’t show severity), when used together with Severity Rate (SR) and Incident Rate (IR), it provides a comprehensive view of safety performance.
For safety professionals, mastering FR is essential not only for reporting and compliance but also for NEBOSH, OSHA, and HSE interview preparation.
👉 Key takeaway: FR = Frequency of accidents per 1,000,000 hours.
👉 The lower the FR, the stronger the safety culture.
🔧 Calculate Frequency Rate with Our Free Tool
Manually calculating FR can sometimes be confusing. That’s why we’ve created an easy-to-use Frequency Rate Calculator on our dedicated site: The HSE Tools.
With this tool, you can:
✅ Enter number of injuries and manhours worked.
✅ Instantly get the Frequency Rate (FR) result.
✅ Download the result in PDF format for your records and reports.
✅ Use it in monthly reports, audits, or even for interview preparation.
👉 Try it now: Frequency Rate Calculator – The HSE Tools
🔗 External Reference
For further reading: International Labour Organization (ILO) – Safety and Health Statistics
How to Calculate the Safe Working Load (SWL) of a Lifting Sling
Crane Safety: How to Calculate Capacity?
Safety Factor of Lifting Equipment
Mr.Lanjewar,
Thank you so much for the many SHE insights you have been providing. I am a SHE student from Angola, and appreciate the timely, accurate information.