Incident rates · Lost workdays · 1,000 h
Calculate lost-workday severity rate and check the reporting base
Calculate recorded lost workdays per 1,000 hours worked, with the reporting basis clearly stated.
By HSECalc · Published
Check that this method fits your task
This version uses the 1,000-hour formula in the ILO training reference. Other schemes use different bases and day definitions; this is not a medical severity assessment.
Choose your inputs and work through the steps
- Confirm how your scheme defines a lost workday and assigns it to the reporting period. Do not mix calendar-day and workday conventions.
- Use the recorded day total and actual hours for the same scope. A count of injured people is not the numerator for this worksheet.
- Apply the stated 1,000-hour base. If another report uses a different base, convert carefully before making a comparison.
Severity rate = lost workdays × 1,000 ÷ hours worked. This page fixes the base at 1,000 and does not assign notional days to fatalities or permanent impairment.
A worked example
Illustrative values explain the tool; they are not prescribed inputs for your work.
- 30 recorded lost workdays × 1,000 = 30,000.
- 30,000 ÷ 200,000 hours = 0.15.
- Report 0.15 lost workdays per 1,000 hours, not 0.15 cases.
Read the result and decide what needs checking
This is an aggregate time-loss measure. It does not diagnose an injury or show all of its consequences.
Keep restricted-duty days, weekends and notional day assignments out of the calculation unless the selected reporting rules explicitly require them. The tool does not invent equivalent days for fatalities.
Common questions
Why does another calculator show a different result?
It may use a million-hour or 200,000-hour base, or another lost-day definition. Check both before comparing.
Should I include weekends or restricted-duty days?
Use the specific reporting scheme’s definitions; do not mix workdays, calendar days and restricted-duty days.
Can this identify the severity of an individual injury?
No. It is an aggregate time-loss rate and does not diagnose or grade an injury.
References and scope notes
Use the current official guidance and the instructions for your actual equipment. HSECalc is independent; a reference is not an endorsement. Read how we use methods and sources or report a correction.