How Do I Calculate Accident Severity Rate and Man-Hours Worked Annually?

Could anyone guide me on the calculation of accident severity rate?

Accident Details

Total number of injuries: 12

Average lost time for injury: 15 days

Total number of employees: 250

Total work hours in a day: 8 hours

Weekly working days: 6

Calculation Query

How can I calculate the man-hours worked per month or year?

Please find the attached file. Similar calculations are acceptable for industries. Things become complicated when you want to calculate the exact working hours, including overtime of employees, and timing deductions for employees who were on leave, etc. There's a lot involved.

It's better to track the exact working hours with the help of an electronic punching card or let the individuals handling manpower (mainly HR/ER/IR) calculate the man-hours worked and provide the data to the safety personnel for further safety rate calculations.

Hope this helps.

Regards

What is the use of Accident Frequency Rate and Severity Rate calculation? For what purpose do we calculate these things? And why are 6000 days debited from the total man-hours?

I am very confused, friends. Please provide me with information.