Work out risk matrix score instantly with clear inputs, formula shown and shareable results.
A five by five risk matrix multiplies likelihood by severity to give an inherent score from one to twenty-five. Applying an effectiveness factor for existing controls gives the residual score, which is what determines whether work may proceed. Scoring inherent and residual risk separately makes the value of the controls visible.
Risk score
Inherent = likelihood x severity; residual = inherent x (1 - control effectiveness)
Bands
Very low below 3, low 3-4, moderate 5-9, high 10-14, extreme 15 and above
Preliminary estimate only. Risk assessment must be carried out by a competent person using the matrix and criteria adopted by your organisation.
Inherent = likelihood x severity; residual = inherent x (1 - control effectiveness). A five by five risk matrix multiplies likelihood by severity to give an inherent score from one to twenty-five.
No control is perfect and all can be bypassed, degrade or be misapplied. Capping effectiveness below 100 percent forces the residual risk to remain visible and monitored.
This calculator takes 3 inputs: Likelihood score, Severity score, Effectiveness of existing controls. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.