Safety – Accident frequency rate calculation

Accident frequency rate calculation

Accident frequency rate calculation

Accident frequency rate formula

The formula for calculating your accident frequency rate is the number of reported accidents multiplied by 200,000, divided by the  number of employee hours worked.Accident frequency rate formula

The number of reported accidents is derived from your operations, as is the total hours worked, while the number 200,000 is used in a number of safety KPI's to standardise the AFR and express it as the number of accidents per 100 employees (200,000 equals 40 hours per week x 100 employees x 50 weeks per year).

Different companies pull and derive their accident data from different places. For some companies, the OSHA 300 log is what is used to record and analyse workplace accidents. Simply counting this table will be enough for companies who record accidents this way, while other companies will need to pull the data from other places like spreadsheets, management systems or specific files.

Accident frequency rate calculation

As you can see from the above, the accident frequency rate is straightforward formula and easy to calculate.

The main mediums companies use for crunching these numbers include:

  • Excel spreadsheets
  • Online calculators
  • Dedicated safety software
  • Physical calculators

Each of these calculators comes with a few pros and cons:

  • Excel spreadsheets can be quickly and easily updated and tracked against historic numbers
  • Online calculators and physical calculators can be used to make the calculation but don't have any additional context
  • Dedicated software gives you a place for tracking and analysing the AFR but requires costs/investment

We have an example calculation below which shows what your real-world calculation may look like.

Let's take a case where a company has had 4 recorded accidents in the previous year, and are looking to do an AFR calculation for the previous year.

Getting the figures together, they have:

  • 4 recorded accidents
  • 200,000 to standardise the number per 100 employees over 12 months
  • A total of 115,000 hours worked across the company or project

So the formula would be:

(4 reported accidents x 200,000) / 115,000 = 6.95

The result here is 6.95 accidents per 100 employees, which could be relatively high depending on the industry.

You can see more AFR industry averages here.

Ways to make your AFR calculation more accurate and reliable

Your AFR number is important for a number of internal reasons and purposes, but it can also have a large impact on external factors including audits and insurances.

Because of this, it's important to get your AFR numbers and the resulting calculation right.

As we know, there are two variables in the calculation which we can make more accurate and impact: the reported accidents and the total numbers of hours worked.

Reporting too many or too few accidents can drastically alter the final number, especially if you have relatively small projects or a small company.

And not getting an accurate measure on the total numbers worked will also skew the final result.

As with most calculations and metrics, the difficulty in any AFR measurement comes in collecting the data properly and efficiently, Finding smarter ways to document and keep track of this data is by far the quickest and most reliable way to sure up your AFR calculations.

It's also what the auditors and other authorities will be looking at and analysing if there are any red flags in your results or procedures.

The accident frequency calculation is the end result of a years worth of collected data, and is the culmination of many safety meetings and process changes.

Take a real look at your ending AFR result and use it as an indicator of safety performance and success, but also focus on how you are collecting and tracking all of your safety information - because that is going to be incredibly useful in making informed decisions about how to improve - and ultimately lowering that AFR number.


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About Lance Hodgson

Lance is VP of Marketing at Sitemate. His aim is to bring awareness to a brighter future for the Built World where industrial workers and companies work smarter.

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