LTIFR Calculator
The Lost-Time Injury Frequency Rate normalises injury counts against exposure hours so sites of different sizes can be compared.
Enter Values
How to use this calculator
- Enter the number of lost-time injuries (LTIs) recorded in the period.
- Enter the total hours worked by all workers in the same period.
- Optionally add total recordable injuries to also get TRIFR, or change the base (some organisations use 100,000 or 200,000 hours instead of 1,000,000).
How it works
The Lost-Time Injury Frequency Rate normalises injury counts against exposure hours so sites of different sizes can be compared. The standard formula is LTIFR = (number of lost-time injuries × 1,000,000) ÷ total hours worked. The result is the number of lost-time injuries you would expect per one million hours worked. TRIFR uses the same formula but counts all recordable injuries (medical treatment, restricted work and lost-time cases combined) instead of only lost-time injuries.
The base multiplier is a convention, not a physical constant — 1,000,000 hours is the most common (roughly 500 full-time workers over a year), but some jurisdictions and companies use 100,000 or 200,000 hours, which simply rescales the result. Whatever base you pick, use the same base and consistent injury definitions across every period so the trend is meaningful. This tool is pure arithmetic and does not decide which incidents qualify as lost-time or recordable — that classification follows your local WHS/OSH rules.
Worked example
3 lost-time injuries over 450,000 hours. A site records 3 lost-time injuries across 450,000 hours worked. LTIFR = 3 × 1,000,000 ÷ 450,000 = 6.67 lost-time injuries per million hours worked. Adding 8 total recordable injuries gives TRIFR = 8 × 1,000,000 ÷ 450,000 = 17.78 per million hours.
Common mistakes
- Mixing up LTIFR and TRIFR — LTIFR counts only injuries that caused time off work, while TRIFR counts all recordable injuries, so TRIFR is always equal to or higher than LTIFR.
- Using different base hours (e.g. 200,000 one quarter and 1,000,000 the next) so the rates can't be compared — keep the base fixed.
- Entering hours for only part of the workforce, or leaving out contractor hours, which inflates the rate. Total hours must cover everyone exposed during the period.
Frequently asked questions
What is a good LTIFR?
There is no universal 'good' number — it depends heavily on industry, workforce size and how injuries are classified. Lower is better, and the most useful comparison is your own trend over time and against published benchmarks for your specific industry and jurisdiction. Treat this figure as guidance, not a compliance verdict.
What's the difference between LTIFR and TRIFR?
LTIFR (Lost-Time Injury Frequency Rate) counts only injuries serious enough to keep someone off work, per million hours. TRIFR (Total Recordable Injury Frequency Rate) counts all recordable injuries — medical treatment, restricted work and lost-time cases — per million hours. Both use the same formula; only the injuries included differ.
Why is the base 1,000,000 hours?
It's a widely used convention that makes the rate easy to interpret as 'injuries per million hours worked', roughly equivalent to a year of work for about 500 full-time employees. You can change the base field to 100,000 or 200,000 if your organisation or regulator uses a different convention — just keep it consistent across periods.
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Cite this tool
Zerdly. (2026). LTIFR Calculator. Retrieved from https://www.zerdly.com/tools/ltifr-calculator/
Tip: Enter any known values to calculate the remaining results.
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