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Lost Time Injury Rate Calculator

Work out lost time injury rate instantly with clear inputs, formula shown and shareable results.

About Lost Time Injury Rate Calculator

Lost time injury frequency rate counts only injuries causing at least one full shift away from work, normalised to a base of exposure hours, usually a million. Restricting the count to lost time injuries makes the measure less sensitive to first aid reporting practice but also much noisier for small organisations.

Formula

Lost time injury frequency rate

LTIFR = lost time injuries x base hours / hours worked

Worked example

With the default values below, Lost Time Injury Rate Calculator returns Lost time injury frequency rate of 6.000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Lost time injuriesminimum 0
3
Hours workedminimum 1 h
500,000 h
Base hours for the rateminimum 1 h
1,000,000 h

Results

Lost time injury frequency rate
6.000
Rate per 200,000 hours
1.200
Hours worked per lost time injury
166,667 h
Expected injuries per 250,000 hours
1.500

Step by step

  1. 1Values used
  2. 2Lost time injury frequency rate
  3. 3Lost time injury frequency rate= 6.000
  4. 4Rate per 200,000 hours= 1.200
  5. 5Hours worked per lost time injury= 166,667 h
  6. 6Expected injuries per 250,000 hours= 1.500

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Lost Time Injury Rate figure worked out?

LTIFR = lost time injuries x base hours / hours worked. Lost time injury frequency rate counts only injuries causing at least one full shift away from work, normalised to a base of exposure hours, usually a million.

Why is LTIFR volatile for small sites?

With few injuries, a single event moves the rate dramatically. A site working 100,000 hours a year sees its rate jump by ten points per injury on a million hour base.

What values do I need to enter?

This calculator takes 3 inputs: Lost time injuries, Hours worked, Base hours for the rate. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.

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