LTIFR and Injury Severity Rate Calculator
LTIFR and severity rate are the headline safety KPIs for many manufacturing groups, mining and construction clients, and supplier audits outside the US. This calculator keeps the arithmetic and the basis consistent.
Your numbers
Cases that resulted in at least one lost day or shift under your definition.
Use scheduled work days or calendar days consistently with your policy.
All employees, including overtime and, if policy says so, contractors.
Your company or customer target on the same basis.
Your results
Definitions of lost time injury, day counting and included workers vary by country, company and customer. Use the definition your contract or regulator specifies.
LTIFR by number of lost time injuries
Sweeps Lost time injuries in period from 0 to 12, holding your other inputs fixed.
Safety KPI view from ERP data
Optional review of how hours worked and incident counts can feed a monthly KPI report.
Optional. The tool and every export work without this. No spam.
How to use it
Enter the lost time injuries, total days lost and total hours worked for the same reporting period and the same population. Pick the rate basis your group uses. Many European and Australian companies report per million hours, US OSHA statistics use 200,000 hours, and some older systems use 100,000. Add your target to see the gap and the number of injuries you can afford before breaching it. The chart shows how the rate rises with each additional case on your hours base.
The formulas
LTIFR = lost time injuries x basis / hours worked. Severity rate = days lost x basis / hours worked. Average days per injury = days lost / lost time injuries. Because the same hours base sits in both rates, severity rate divided by LTIFR returns the average days per case. A site with a very low frequency but a high average days figure is having few but serious injuries, which a frequency number alone hides.
- Keep the basis constant in a trend report
- Report both rates, not one
- Define how days are counted before comparing sites
Reading the output
Compare frequency to a target and severity to the history of your own plant. Small plants swing sharply: with 150,000 hours a year, one injury at the million-hour basis gives an LTIFR near 6.7, so use rolling twelve-month figures and show the case count beside the rate. The allowed-injury output turns an abstract target into a number a supervisor can act on, such as two cases for the year.
Common mistakes
The usual errors are mixing contractor hours into the denominator but not their injuries, comparing a million-hour rate with a 200,000-hour rate, and counting restricted work days in one place but not another. Also remember that a rate rewards under-reporting. Pair it with near miss counts and leading indicators so a quiet year is not mistaken for a safe one.
Frequently Asked Questions
What is the LTIFR formula?
LTIFR equals the number of lost time injuries multiplied by the rate basis, usually 1,000,000, divided by the total hours worked in the period. Use the same period and population for the numerator and the denominator.
What is the difference between LTIFR and TRIR?
LTIFR counts only injuries that cause lost time. TRIR counts all recordable cases, including medical treatment and restricted work, and is usually on a 200,000-hour basis. They answer different questions, so do not substitute one for the other.
How is severity rate different from frequency rate?
Frequency rate shows how often lost time injuries happen. Severity rate shows how many days were lost per unit of exposure. A plant can have a low frequency and a high severity if a few cases are serious.
Which hours basis should I use?
Use whatever your corporate group, customer or regulator requires. A million-hour basis is common internationally, 200,000 hours is typical for US OSHA based reporting. Never compare rates calculated on different bases.
If hours worked sit in payroll and incident data sits in another system, we can help build a monthly safety KPI view over your ERP data without manual copy and paste.
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