Should commuting accidents be counted?

Conventions vary between organisations and between countries. What matters is to set the rule in your procedure, write it down, and stop changing it: a series of indicators is only worth something if it remains comparable with itself over time.

What is the difference between the frequency rate and the frequency index?

The frequency rate relates injuries to hours worked, the frequency index relates them to headcount. The first neutralises variations in working time, the second compares more easily between organisations of similar size.

Does ISO 45001 require these indicators?

No. The standard requires occupational health and safety performance to be monitored, measured, analysed and evaluated, and the chosen indicators to be relevant to the organisation. It requires neither the frequency rate, nor the severity rate, nor any particular formula: these are widely used professional conventions, not normative requirements.

Are these figures sent to HEMC?

No. The calculation runs entirely in your browser. None of the data entered is transmitted, stored or linked to your organisation.

What these three indicators are for

The frequency rate measures how many injuries occur per volume of hours worked: it answers the question of recurrence. The severity rate measures the weight of their consequences in days lost: it answers the question of severity. An organisation can have few but very serious injuries, or the opposite, and only the two read together give an accurate picture. The frequency index, related to headcount rather than hours, mainly serves comparison with organisations of similar size.

Your indicators for the period

Enter the hours worked as a minimum, then whatever data you have.

Base used for the frequency rate

These two bases do not count the same events: the French frequency rate counts lost time injuries, the North American TRIR counts recordable cases. A result obtained on one base therefore cannot be compared with the other, even after conversion.

Lost time injuries in the periodInjuries leading to at least one day away from work.Working days lostCalendar days of absence counted within the period.Hours worked in the periodHours actually worked, all employees combined.Average headcount (optional)Only needed for the frequency index.

Enter at least the hours worked to obtain a result.

The figures you enter stay in your browser: they are neither transmitted, nor stored, nor linked to your organisation.

How the calculation is carried out

1
Set the period
Month, quarter or year. All three indicators must cover the same period as the hours worked, otherwise the ratio means nothing.
2
Count the hours actually worked
These are hours of effective presence, not contractual hours: leave, absence and time off are excluded. It is the denominator of both rates, and therefore the costliest mistake.
3
Retain lost time injuries
An injury with no time away from work does not enter the French frequency rate. Commuting accidents follow their own rule: state in your procedure whether you include them, and keep the same convention from one period to the next.
4
Count the days lost
Days of absence counted within the period, including those arising from an injury that occurred in an earlier period and is still ongoing.
5
Read the result over time
A single figure says nothing. It is the twelve-month rolling trend, and the gap between frequency and severity, that guide action.

The most common calculation mistakes

Using contractual hours instead of hours actually worked, which mechanically understates both rates.
Changing convention mid-year, for instance by including commuting accidents from one quarter onwards: the series is no longer comparable with itself.
Comparing a frequency rate on a 1,000,000 base with a TRIR on a 200,000 base, even after conversion, when the events counted differ.
Leaving out agency staff and contractors present on site, whose hours and injuries often fall within the reporting perimeter.
Tracking only the frequency rate: an organisation can improve its frequency while the severity of its injuries worsens.
Stopping the count of days lost at the end of the period while the absence continues, which artificially shifts severity to the next period.

Frequently asked questions

Should commuting accidents be counted?: Conventions vary between organisations and between countries. What matters is to set the rule in your procedure, write it down, and stop changing it: a series of indicators is only worth something if it remains comparable with itself over time.
What is the difference between the frequency rate and the frequency index?: The frequency rate relates injuries to hours worked, the frequency index relates them to headcount. The first neutralises variations in working time, the second compares more easily between organisations of similar size.
Does ISO 45001 require these indicators?: No. The standard requires occupational health and safety performance to be monitored, measured, analysed and evaluated, and the chosen indicators to be relevant to the organisation. It requires neither the frequency rate, nor the severity rate, nor any particular formula: these are widely used professional conventions, not normative requirements.
Are these figures sent to HEMC?: No. The calculation runs entirely in your browser. None of the data entered is transmitted, stored or linked to your organisation.

Sources and verification

Values and definitions verified on 2026-08-02.

Indicative result. It helps you position yourself; it replaces neither a specialist's analysis nor the reporting obligations that apply to your activity.

Tools · ISO 45001

Lost time injury frequency and severity rate calculator

The three indicators every health and safety manager recalculates each month. Enter your figures for the period and the result appears immediately.