Free tool for UK builders

Risk matrix calculator

Pick a likelihood and a severity from 1 to 5. You will see the risk score, its band and what the band means, before and after controls, on a 5 × 5 matrix.

Score a hazard

Pick how likely it is that the hazard causes harm, and how severe the harm could be. Your scores stay in your browser. Nothing you choose is sent to us.

Before controls

Likelihood

Severity

Add a rating after controls

Pick a likelihood and a severity to see the score.

5 × 5 risk matrix: likelihood × severity = score
Severity \ Likelihood	1. Very unlikely	2. Unlikely	3. Possible	4. Likely	5. Very likely
5. Fatality or permanent disability	5	10	15	20	25
4. Major injury or long-term illness	4	8	12	16	20
3. Serious injury or illness	3	6	9	12	15
2. Injury needing treatment	2	4	6	8	10
1. Minor injury	1	2	3	4	5

How the score works

The score is the likelihood multiplied by the severity, so it runs from 1 to 25. The three bands are the ones in our risk assessment guide:

1–4Low risk. Acceptable with current controls. Monitor and maintain.
5–12Medium risk. Additional controls are needed. Review whether you can reduce the likelihood or severity further.
13–25High risk. Work should not proceed until additional controls bring the risk down. Consider whether the activity can be eliminated or done a completely different way.

The matrix is a tool for prioritisation, not an exact science. Record the rating before controls and the rating after them, so your RAMS shows what the controls do.

Do I have to use a risk matrix?

No law sets a risk matrix. Under the Management of Health and Safety at Work Regulations 1999, employers must make a suitable and sufficient risk assessment. HSE says the minimum is to identify what could cause injury or illness, decide how likely it is that someone could be harmed and how seriously, and take action to eliminate the hazard or control the risk.

A matrix is one common way to record that judgement. Scales and bands vary between firms: some use 3 × 3, some use 5 × 5, and bands differ. Use the one your firm or your client uses, and say which in your RAMS. HSE’s own risk assessment template has no scoring matrix: it records who might be harmed and how, what you are already doing, what further action is needed, who does it and by when.

If you employ 5 or more people, HSE says you must record your significant findings. A score alone is not enough: the record needs the hazards, who might be harmed and how, and what you are doing to control the risks.

This page covers Great Britain. Northern Ireland has its own Management of Health and Safety at Work Regulations (Northern Ireland) 2000. This is general guidance, not legal advice.