Guide

The Risk Assessment Matrix Explained

A risk matrix turns a judgement call into a repeatable score. By rating each hazard on how *likely* it is and how *bad* it would be, you can rank risks consistently and put your effort where it matters most.

Generate a risk assessment How to do a risk assessment

A person in a hi-vis vest pointing at a 5-by-5 risk matrix heatmap that runs from green in the bottom-left to red in the top-right. — A risk matrix plots likelihood against consequence, shading the highest-priority risks red.

What a risk matrix is

A risk matrix (or risk assessment matrix) is a grid used to rate and rank risks. One axis is the likelihood that a hazard causes harm; the other is the consequence — how serious that harm would be. Where the two meet gives a risk score, and that score maps to a colour band, from low (green) to extreme (red).

The most common format is the 5×5 matrix: five levels of likelihood and five of consequence, producing a score from 1 to 25. It is popular because it is detailed enough to separate real priorities but simple enough to use on site in seconds. RiskForms uses exactly this 5×5 model.

The likelihood scale

How probable is it that the hazard actually causes harm, given the work and the controls in place?

Score	Rating	What it means
1	Rare	Would only happen in exceptional circumstances.
2	Unlikely	Could happen, but not expected.
3	Possible	Might happen at some point.
4	Likely	Will probably happen at some point.
5	Almost certain	Expected to happen, often or repeatedly.

The consequence scale

If the harm did occur, how severe would the outcome be for the people affected?

Score	Rating	What it means
1	Insignificant	No injury or first aid only.
2	Minor	Minor injury needing basic medical treatment.
3	Moderate	Injury requiring medical treatment or lost time.
4	Major	Serious injury or long-term health effect.
5	Catastrophic	Fatality or permanent disability.

The 5×5 matrix and score bands

Multiply likelihood by consequence (each 1–5) to get a score from 1 to 25, then read off the band. Expand the matrix below to see exactly how every cell is coloured.

How risk ratings & colours are calculatedShow matrix

Each row is scored likelihood × consequence (each 1–5), giving a score from 1 to 25. The score maps to a band and colour. We score risk before controls (initial) and after controls (residual).

Low · score 1–3Moderate · score 4–6High · score 7–12Extreme · score 13–25

	Consequence →
	1 Insignificant	2 Minor	3 Moderate	4 Major	5 Catastrophic
5 Almost certain	5	10	15	20	25
4 Likely	4	8	12	16	20
3 Possible	3	6	9	12	15
2 Unlikely	2	4	6	8	10
1 Rare	1	2	3	4	5

↑ Likelihood. Rows top-to-bottom run 5 (almost certain) down to 1 (rare).

How to read the score

The score is simply likelihood × consequence. A hazard that is *possible* (3) and would be *major* (4) scores 12; one that is *almost certain* (5) and *catastrophic* (5) scores the maximum of 25. Those scores fall into four bands: Low (1–3), Moderate (4–6), High (7–12), and Extreme (13–25) — which is why the top-right corner of the grid is red and the bottom-left is green.

Crucially, you score each risk twice: once *before* controls (the initial risk) and once *after* your controls are in place (the residual risk). The drop between the two is the evidence that your controls actually work. A good assessment shows a high initial score falling to a low residual score once the hierarchy of controls has been applied.

Using a matrix well

A matrix is a tool for thinking, not a substitute for it. Keep these in mind.

Be consistent

Agree what each rating means before you start, so the same hazard gets the same score whoever assesses it. Shared definitions matter more than the exact numbers.

Score residual risk too

The initial score justifies action; the residual score proves the controls brought the risk down to an acceptable level.

Don't hide behind the number

A neat score of 6 can mask a genuinely dangerous task. Use judgement — if something feels unsafe, treat it that way.

Prioritise, then act

The point of ranking risks is to tackle the reds and oranges first. A matrix that never changes what you do is just decoration.

Where the matrix fits

Scoring risk is the third step of a risk assessment — after you've identified the hazards and before you finalise controls. For the full sequence, see how to do a risk assessment.

RiskForms scores every line of your assessment on this exact 5×5 matrix automatically, showing both the initial and residual risk in the correct colour band — so the ranking is done for you and stays consistent across every document.

Keep reading

How to do a risk assessment

Step-by-step walkthrough

What is a risk assessment?

Definition & legal context

Hazard identification

Spotting hazards before work

Risk matrix explained

5×5 likelihood × consequence

Hierarchy of controls

Elimination through to PPE

Job Hazard Analysis (US)

OSHA JHA / JSA

SWMS (Australia)

Safe Work Method Statement

RAMS (UK)

Risk Assessment & Method Statement

SSSP (New Zealand)

Safe System of Work Plan

Job Hazard Analysis (Canada)

Provincial & federal JHA

See the matrix in action

Describe your task and RiskForms scores each risk on a 5×5 matrix — initial and residual — in your region's format, ready to review and sign.

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