Complete Guide to ILO Fatigue Allowances

Key Points:

• ILO allowances cover the operator's personal needs, basic fatigue and adverse job conditions, on top of unavoidable delays.
• The classic work measurement literature includes two constant allowances: one for personal needs (around 5% of basic time) and basic fatigue (4% for light work under good conditions).
• Variable allowances are added according to the job's posture, physical effort, environment, mental load or noise.

Introduction to Fatigue Allowances: Fatigue allowances are additional times added to the basic time of a task to compensate for physical and mental fatigue, personal needs and unavoidable delays. Without them, the standard time would be unworkable in daily practice: a standard must be sustainable day after day without eroding the operator's health.

Structure of Allowances: The work measurement literature, starting with the ILO manuals —Introduction to Work Study, edited by George Kanawaty (4th edition, 1996)— groups allowances into two blocks:

1. Constant allowances: they cover the operator's personal needs (physiological breaks and other unavoidable interruptions) and the basic fatigue of the job. For light work, seated and under good conditions, the classic literature considers a 4% basic fatigue allowance sufficient; harsher job conditions will raise that figure.
2. Variable allowances: they apply according to the specific job conditions —posture, use of force or muscular energy, lighting, atmosphere (temperature, humidity, ventilation, fumes, dust), required attention, noise, mental strain, monotony and tediousness—. Each one depends on the severity of the factor, not on a universal fixed percentage.

Calculation of Allowances:

1. Determine the basic time of the task through time study, with the corresponding performance rating.
2. Add the constant allowances (personal needs and basic fatigue).
3. Add the variable allowances matching the job conditions.
4. The result over the basic time is the standard time: ST = NT × (1 + Σ allowances). For example, with a normal time of 10 minutes and 10% of allowances, the standard time is 11 minutes.

Practical Application: What really matters is assessing the workplace before choosing percentages:

• Work environment analysis: observe posture, physical effort and environmental conditions through direct observation of the workplace.
• Measuring environmental factors: measure temperature, noise or lighting with suitable instruments and assign the corresponding allowance.
• Workload assessment: classify the work as light, medium or heavy to determine the effort allowance.

In Cronometras, ILO and TAL allowances are configured by factors —use of force, posture, vibrations, short cycle and annoying clothing; concentration, monotony, visual strain and noise; temperature and humidity, ventilation, fumes, dust, dirt and presence of water— and the application applies them when calculating the standard time.

Validation and Recommendations:

• Checking results: compare calculated standard times with real observation and adjust if the standard cannot be sustained over a shift.
• Periodic reviews: revisit the allowances when job conditions change (machinery, environment, work organisation).
• Process documentation: record which factors were applied and to what extent, for future reference and audits.
• Listen to the operator: their perception of the real workload is the best detector of forgotten factors.

Note: the specific percentages vary with the reference table and version used; it is advisable to fix one table and apply it consistently across all plant studies.

Applying allowances properly is what separates a credible standard time from one that only works on a spreadsheet: it reflects the real working conditions and that is why it holds up in planning and in agreement with the team.

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