Injury severity Rate (ISR)
This is defined as the number of days lost due to injuries for 100 man hours worked.
ISR = Number of days lost x 1000 number of man hours worked
Injury Frequency Rate (IFR)
This is defined as the number of disabling injuries per one-hundred thousand man hours worked.
IFR = Number of disabling injuries x 100000 total number of man hours worked
Injury Index
Injury Index= (ISR x IFR )/ 1000