14
Risk Calculation
Description Likelihood
Unwanted event is almost certain
to happen in the next year
(or 90% or greater chance of
occurrence)
(5) Almost
Certain
High probability for unwanted
event to occur in the next year
(or between 50% ‐90% chance of
occurrence)
(4) Very
Likely
It is possible for unwanted event
to occur in the next year
(or between 20% ‐50% chance of
occurrence)
(3) Likely
Low probability for unwanted
event to occur in the next year
(or between 5% ‐20% chance of
occurrence)
(2) Unlikely
Very low probability for unwanted
event to occur in the next year
(or less than 5% chance of
occurrence)
(1) Rare
Description Consequence
Fatality or permanent
disability
(or extreme
impact/importance)
(5) Extreme
Serious event / critical injury
or illness
(or major
impact/importance)
(4) Major
Temporary disability (lost
time): Injury/illness
(or moderate
impact/importance)
(3) Moderate
First aid treatment (no lost
time)
(or minor
impact/importance)
(2) Minor
No injury or illness
(or negligible
impact/importance)
(1) Low
Risk Rating Matrix
25 20 15 10 5
Almost
certain
Likelihood
20 16 12 8 4
Very
Likely
15 12 9 6 3
Likely
10 8 6 4 2
Unlikely
5 4 3 2 1
Rare
Extreme Major Moderate Minor Low
Consequence
Risk Rating
Low Moderate High Critical
0.00 –4.99 5.00 –11.99 12.00 –19.99 20.00 –25.00
