Use the free risk matrix calculator
Available on all plans
The risk matrix calculator multiplies a likelihood score by a severity score, from 1 to 5 each, and shows the risk score and band on a 5 x 5 matrix. It's free and you don't need an account. You can also find it on the free tools page.
Score a hazard
Open the risk matrix calculator from the free tools page
Under Before controls, choose a Likelihood and a Severity
To score the risk after controls, tick Add a rating after controls and choose both scores again
Read Risk before controls and Risk after controls, with the band and what it means
The matrix below the result marks where each rating falls. Click Start again to clear your scores.
Frequently asked questions
Do I need an account to use the risk matrix calculator?
No. The risk matrix calculator is free to use on our website without signing in.
Are my scores sent to The Site Book?
No. The calculator works out the score in your browser. Your scores are not sent to us or saved.
Does the law say I must use a risk matrix?
No. HSE says the minimum is to decide how likely it is that someone could be harmed and how seriously. A matrix is one common way to record that, and scales vary between firms.
Related guides
Not using The Site Book yet? Start your first job free.
Start free →Didn't answer it? Email [email protected] — we'll get back to you by email.