Engineering CalculationLTIFR, Frequency Rate & Severity Rate Calculator (IS 3786 / OSHA)
Calculate the accident statistics that safety officers report every month: frequency rate, severity rate, incidence rate, LTIFR and TRIR.
Open the calculator →Formula
Frequency rate = lost-time injuries × 1,000,000 / man-hours worked (IS 3786)
Severity rate = man-days lost × 1,000,000 / man-hours worked (IS 3786)
TRIR = recordable cases × 200,000 / hours worked (OSHA)
Worked example
3 lost-time injuries, 90 man-days lost, 1,200,000 man-hours
Frequency rate = 3 × 1,000,000 / 1,200,000 = 2.50
Severity rate = 90 × 1,000,000 / 1,200,000 = 75.0
Where engineers use it
- Monthly safety MIS for factories and construction sites
- Safety committee and management reports
- Contractor safety performance
How to use
- Click Open the calculator. It runs free in your browser, on desktop or phone.
- Enter your values. Units and typical ranges are shown next to each input.
- Read the result and the step-by-step working, then print or add it to your Project BOQ.
Questions
Which multiplier should I use?
IS 3786 uses one million man-hours; OSHA TRIR uses 200,000 hours. The tool shows both so you can report to either.