In brief
In the L-type matrix, risk is found by probability × severity; both axes are scored from 1 to 5 and the result is between 1 and 25. The method's reliability depends on defining the scale steps in a concrete and measurable way for your workplace. In small and medium-sized workplaces with similar tasks, it is faster and easier to understand than Fine-Kinney; on production lines with very different exposure frequencies, however, it may not separate priorities sufficiently.
What is L-type matrix risk analysis, and where does it stand in the legislation?
L-type matrix risk analysis asks two questions for each hazard: how likely is the harm, and how severe would it be if it occurred? Both answers are scored from 1 to 5 and multiplied:
R = P × S (Probability × Severity)
The Regulation on Occupational Health and Safety Risk Assessment does not mandate a specific method. Article 9 requires that, for each hazard identified, how often the risk may occur and how severe the harm may be are determined, taking into account the effect of existing control measures. The 5x5 matrix directly meets these two requirements. The method used is stated in the document; putting the scoring tables in an annex to the document ensures that the team and the inspector speak the same language.
We explain the general flow of risk assessment in our article on how to carry out a risk assessment, and the three-factor alternative in our article on the Fine-Kinney method. This article focuses on setting up the matrix and using it correctly.
How is a 5x5 risk matrix set up?
The rows of the matrix show probability and the columns show severity; each cell is the product of the two. The values that can arise in a 5x5 matrix are: 1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 16, 20 and 25.
| Probability ↓ / Severity → | 1 Very minor | 2 Minor | 3 Moderate | 4 Serious | 5 Very serious |
|---|---|---|---|---|---|
| 5 Very high | 5 | 10 | 15 | 20 | 25 |
| 4 High | 4 | 8 | 12 | 16 | 20 |
| 3 Medium | 3 | 6 | 9 | 12 | 15 |
| 2 Low | 2 | 4 | 6 | 8 | 10 |
| 1 Very low | 1 | 2 | 3 | 4 | 5 |
Setting it up consists of four steps:
- Define the scales. Write what each step means using examples specific to your workplace (next section).
- Set the risk classes. Write which score falls into which class and what is done in each class.
- Calibrate the team. Have the assessment team score the same three hazards separately; differences are resolved through discussion.
- Score and prioritise. Score each hazard with existing measures, then score it again after the measure.
Probability-severity matrix: write the scale definitions for your workplace
The weakest point of the matrix is vague expressions such as "medium probability". What one person calls "medium", another calls "high", and the result varies with the person. To prevent this, link each step to criteria that can be observed in your workplace.
Probability scale (example):
| Score | Definition | How is it decided? |
|---|---|---|
| 1 Very low | Not expected | Access to the hazard is physically prevented; no similar incident known |
| 2 Low | Rarely | Measures are in place and working; defeating them requires an unusual chain of errors |
| 3 Medium | Occasionally | A measure exists but can easily be bypassed; similar incidents are known in the sector |
| 4 High | Frequently | Measures are incomplete; a near miss has occurred in the workplace |
| 5 Very high | Almost certain | No measures; a similar accident has occurred in the workplace or there is continuous contact with the hazard |
Severity scale (example):
| Score | Definition | Example |
|---|---|---|
| 1 Very minor | Treated with first aid, no lost workdays | Minor scratch |
| 2 Minor | Requires medical treatment, short loss of workdays | Cut requiring stitches |
| 3 Moderate | Incapacity lasting several days or weeks | Sprain, crushing without fracture |
| 4 Serious | Loss of limb, permanent damage, occupational disease | Loss of a finger, hearing loss |
| 5 Very serious | Death or more than one serious injury | Fall from height, fire |
These tables are examples. "Frequently" in an office and "frequently" in a foundry are not the same thing; rewrite them with examples from your own workplace. Using objective criteria such as lost workdays in the severity scale largely frees the scoring from personal interpretation.
Risk matrix colours and action decisions
Risk matrix colours make the result readable at a glance. A common classification in practice is:
| Score | Risk class | Colour | Action |
|---|---|---|---|
| 1 | Negligible | Green | No additional measures needed; existing measures are maintained |
| 2–6 | Low | Green | Existing measures are monitored |
| 8–12 | Medium | Yellow | Included in the action plan; owner and deadline set |
| 15–16 | High | Orange | Measures in the short term; temporary measures until then |
| 20–25 | Intolerable | Red | Work does not start until the risk is reduced; if under way, work is stopped |
Write the boundaries and deadlines clearly in the document. The regulation requires the plan prepared for control measures to include the work steps, the person or department responsible, and start and end dates (Art. 10). Colours are not a decision but a reminder of the decision; if an orange row has no deadline, the matrix has not done its job.
The matrix has a known weakness: the same score can carry different meanings. A scratch with probability 5 and severity 1 and a fatal event with probability 1 and severity 5 both score 5 and appear "low". This is why you should set a rule to review every row with severity 5 separately, regardless of its score. For every hazard with a possibility of death or permanent damage, ask whether there is a measure that would reduce the probability further.
L-type matrix example: a small packaging warehouse
Consider a business in Bursa with 12 employees that stores and ships cardboard packaging. The team consists of the OHS specialist, the workplace physician, the warehouse supervisor and a forklift operator.
| Hazard | Before (P × S) | Justification | Measure | After |
|---|---|---|---|---|
| Forklift striking a pedestrian | 4 × 5 = 20 | No pedestrian route, near miss has occurred | Pedestrian route marking, mirror at blind corner, speed limit | 2 × 5 = 10 |
| Box falling from a rack | 3 × 3 = 9 | Upper shelves stacked irregularly | Stacking rule, rack end netting | 2 × 3 = 6 |
| Back injury from manual handling of boxes | 4 × 3 = 12 | Heavy boxes lifted from the floor | Lifting table, leaving heavy boxes on pallets | 2 × 3 = 6 |
| Fire in cardboard stock | 2 × 5 = 10 | Smoking ban in place but cigarette ends found | Single smoking point outside the building, closing round | 1 × 5 = 5 |
Two lessons emerge from the table. First, the forklift row is still "medium" after the measure; the next step is to separate pedestrian and forklift areas with a physical barrier. Second, severity did not change in any row: the measures reduce the likelihood of the harm occurring, not its magnitude. Severity only falls with measures that reduce energy, such as speed, height or load. For the order of priority in choosing measures, see our article on the hierarchy of controls.
L-type matrix or Fine-Kinney?
Both methods meet the requirements of the regulation; the choice is made according to the structure of the workplace.
Workplaces where the matrix is more practical:
- Places with a small number of similar tasks, such as offices, shops, warehouses and small workshops.
- Situations where the team is new to risk assessment and the result needs to be easily explained to employees.
- Work where exposure frequency does not differ significantly between tasks.
Situations where Fine-Kinney separates better:
- Production lines where the same hazard is encountered on every cycle in one task and once a year in another.
- Large facilities where many rows cluster in the middle zone and prioritisation becomes difficult.
It is also possible to use different methods for different sections in the same document, such as the matrix in the administrative building and Fine-Kinney on the production line. What matters is that the method used in each section is written down. You can find a complete example prepared for a less hazardous office in our article on the office risk assessment example.
Common mistakes
- Not writing scale definitions. Saying "3 = medium" is not enough; what counts as medium must be written down.
- Counting a measure that does not work. A bypassed sensor or unused PPE does not reduce probability.
- Scoring several hazards in one row. "Warehouse" is not a hazard; forklift, racking and manual handling are separate rows.
- Adjusting scores to change the class. Lowering the probability by one step to bring a score of 15 down to 12 makes the method meaningless.
- Confusing hazard and risk. "Forklift" is a hazard source; "a forklift striking a pedestrian" is a risk. We explain the distinction in our article on the difference between hazard and risk.
Carrying out the risk assessment together on site with the matrix or Fine-Kinney and following up the action plan is the subject of our risk assessment service.
Frequently Asked Questions
Is the L-type matrix legally valid?
Yes. The Risk Assessment Regulation does not mandate a specific method; it requires one or more methods suitable for the workplace to be chosen and the method used to be stated in the document. The 5x5 matrix is widely used because it directly meets the probability and severity requirement.
What is an acceptable score in a 5x5 risk matrix?
In practice, 1–6 is considered low and monitored with existing measures. 8–12 is included in the action plan, 15–16 requires measures in the short term, and 20–25 is the class in which work is not permitted until the risk is reduced. State clearly in the document which classification you use.
Should I use a 3x3 or a 5x5 matrix?
A 3x3 matrix can be used in very small workplaces, but its power to distinguish between risks is low. A 5x5 matrix provides more differentiation and is compatible with commonly used classifications. Whichever is chosen, the scale definitions must be written down.
Does the severity score fall after a measure?
Usually not. Guards, barriers or PPE reduce the likelihood of harm occurring. Severity falls only when the factor that determines the magnitude of harm, such as speed, height, load or energy, is reduced.
A risk assessment that identifies and scores hazards on site, links each measure to an owner and a date, and has a clear renewal schedule.
Bursa SİSTEMER OSGB Technical Team — written from the field experience of our OHS specialists and workplace physicians. Legal information is valid as of the publication/update date; contact us for an assessment specific to your business.