The accident injury rate is the frequency of work-related accidents that result in personal injury within a company, privately owned business or organisation. The rate measures the frequency of accidents by using a specific formula regulated by the Health and Safety Executive (HSE). To calculate your business's accident injury rate, plug some of your company statistics into the accident rate formula.

Add together the total amount of work-related injuries and illnesses that have occurred at your company within the past year. Exclude injuries caused by work-related road traffic accidents because they fall outside the HSE's jurisdiction.

Multiply the total amount of work-related injuries and illnesses by 100,000. If your company reported a total of nine work-related injury and illness cases, you would multiply 9 by 100,000, which gives you the total of 900,000. The number 100,000 is the standard used by the HSE Labour Force Survey reference week to cover average number of employees and hours worked.

Divide that number by the total number of employee hours worked to calculate your company's accident injury rate. To calculate the total number of employee hours worked, add together all work hours that have been recorded by every single employee in your company within the past year. For example, if your company has 200 employees, all of whom worked exactly forty hours per week for fifty weeks out of the year, your company would have 400,000 hours of employee hours worked. In this scenario, your company would have an accident injury rate of 2.25 (900,00/400,000 = 2.25).