How do I determine the severity rate?

The severity rate formula is nearly identical to the incidence rate formula. The calculation for an incidence rate follows:

Total number of injuries and illnesses ÷ Number of hours worked by all employees x 200,000 hours = Total recordable case rate

To determine the severity rate, replace the first variable, “Total number of injuries and illnesses,” with the total number of days away and days on job restriction/transfer. Simply add up the number of days recorded in column (K) and column (L) on the 300 Log.

Total number of days away and on restriction/transfer ÷ Number of hours worked by all employees x 200,000 hours = Severity rate

Some industries calculate a Lost Day Severity Rate using only the number of days away from column (L). However, the generic term “severity rate” includes both lost days and days of restriction/transfer.

Severity rates may have increased since OSHA adopted the new 300 Log because under the old rule, employers only counted working days. The 300 Log requires employers to count calendar days. Since the day count now includes weekends, holidays, vacation, and other calendar days, the numbers may be higher.