⏱️ Severity Rate Calculator
How serious your injuries are — days lost per million hours worked.
Severity Rate = (Total days lost × multiplier) ÷ total hours worked. Read it alongside frequency (LTIFR): a low frequency but high severity means fewer but more serious injuries — a different problem to solve.
Frequently asked questions
What is a safety severity rate?
The severity rate measures how serious injuries are rather than how often they happen: the number of workdays lost per million (or per 200,000) hours worked.
How do you calculate severity rate?
Severity Rate = (total days lost × multiplier) ÷ total hours worked, using 1,000,000 or 200,000 as the multiplier. Example: 120 days lost over 1,500,000 hours gives (120 × 1,000,000) ÷ 1,500,000 = 80.
How should severity rate be read alongside LTIFR?
Frequency (LTIFR) tells you how often injuries occur; severity tells you how bad they are. Low frequency with high severity suggests fewer but more serious injuries — often a sign that major-hazard controls deserve attention.
How are fatalities counted in severity rate?
Conventions differ. Some older standards (such as ANSI Z16.1) charged a fixed number of days, commonly 6,000, for a fatality or permanent total disability. Many organisations now report fatalities separately. State whichever convention you use.