Safety · Workplace injury rates
LTIFR calculator.
Enter your lost-time injuries and the hours worked in the same period. Add days lost to get a severity rate too.
4 lost-time injuries over 1,250,000 hours worked is an LTIFR of 3.2 per million hours: 4 x 1,000,000 / 1,250,000. With 36 days lost, the severity rate is 28.8.
Your numbers
Your result
What LTIFR measures
LTIFR is a frequency rate: how often a lost-time injury happens for every million hours worked. Dividing by hours is what lets a 40-person fabrication shop and a 4,000-person mine be compared on one scale. The catch is the phrase “lost time”: this page applies no single definition of it, so two LTIFRs are only comparable when both use the same written definition. That decision is yours, because the formula is the easy part.
If you came here from a U.S. safety form, you may want TRIR instead: it counts OSHA-recordable cases on a 200,000-hour base. The base selector on this page converts an LTIFR to that base for comparison, but a lost-time count and a recordable count are different counts, so the converted number is not a TRIR.
Worked example
A site had 4 lost-time injuries over 1,250,000 hours worked. LTIFR = 4 x 1,000,000 / 1,250,000 = 3.2 per million hours. On the 200,000-hour base the same count is 4 x 200,000 / 1,250,000 = 0.64. The injuries cost 36 days in total, so the severity rate is 36 x 1,000,000 / 1,250,000 = 28.8 days lost per million hours, and the average is 9 days per injury.
How it is calculated
- Frequency rate = injuries x 1,000,000 / hours worked. The International Labour Organization’s statistics resolution defines the frequency rate as the new cases of injury in the year divided by the hours worked by the reference group, multiplied by 1,000,000.
- Severity rate = days lost x 1,000,000 / hours worked, which the ILO material gives as days lost per 1,000,000 hours worked.
- The 200,000-hour option applies the U.S. BLS base, the hours of 100 full-time workers for a year, to the same counts.
Formula as published in the ILO material opened October 26, 2026. The ILO frequency rate counts injury cases in general; applying it to lost-time cases only is the common workplace use, and the definition of lost time is yours.
What this does not cover
- A definition of lost time. No regulator definition was opened for this page, so none is stated; use your own written rule.
- How fatalities, restricted-duty cases and illnesses are handled; decide that in your own definition.
- Any benchmark. Compare only against a published rate that uses your definition.
Sources
Common mix-ups
-
Often assumedAn injury rate of 3.2 means the same thing whichever hours base a report uses.
What the source saysBLS puts incidence rates on a base of 200,000 hours, the hours of 100 employees working 40 hours a week for 50 weeks. A rate quoted per 1,000,000 hours sits on a different base, so the two figures cannot be compared until one is converted. [1]
Checked against these sources on .
Frequently asked questions
What is the LTIFR formula?
Lost-time injuries x 1,000,000 / hours worked. The ILO material defines the frequency rate with the same 1,000,000 multiplier.
What counts as a lost-time injury?
This page applies no single definition. Write down your own rule for what counts as lost time and keep it fixed so year-on-year figures stay comparable.
What is the difference between LTIFR and TRIR?
LTIFR counts lost-time injuries per million hours here; TRIR counts OSHA-recordable cases per 200,000 hours. Different counts and different bases, so one cannot be converted into the other.
What is a severity rate?
Days lost x 1,000,000 / hours worked, per the ILO material. It shows how long injuries keep people away, not just how many there are.
Why is there a 200,000-hour option?
Some reports use the 200,000-hour base from BLS, the hours of 100 full-time workers for a year. The option reports the same count on that base so you can match a form.
Estimate only
This page is a planning aid, not safety, engineering or legal advice. Results use the numbers you enter and the formulas and sources named above, as read on October 26, 2026. Everything runs in your browser; nothing is sent anywhere.