Calculator
Severity rate calculator
Calculate the rate from your chosen event or lost-workday count and the total hours worked. The formula and source are shown below.
Use the same reporting period for the count and hours.
lost workdays per 1,000 hours0.00
Formula and limits
Severity Rate = lost workdays × 1,000 ÷ total hours worked
The ILO training package presents severity rate per 1,000 hours. Definitions of lost days, restricted days and calendar or workdays can differ between reporting systems.
Rates are summaries of recorded outcomes. They do not measure every hazard or prove that work is safe; read them with exposure, event definitions and preventive measures in view.
Source: International Labour Organization. Occupational safety and health: training package (checked 30 October 2026).