---
title: "The PxD matrix"
url: "https://docs.4hse.com/risk-assessment/pxd-matrix"
description: "How the probability and damage matrix is built, the scales it uses, and what the colours mean."
---

# The PxD matrix

The matrix is a Cartesian grid:

-   **Damage (D)** on the X axis — how severe the consequences are if the event happens;
-   **Probability (P)** on the Y axis — how likely the event is to happen.

![The risk assessment matrix](/_astro/risk-evaluation-matrix-2.OqljpyO2_Zic2qO.webp)

## The scales

[Section titled “The scales”](#the-scales)

Both are rated **from 1 to 9**.

Axis

From

To

**Probability**

Unlikely

Very likely

**Damage**

Minor

Very severe

![The definition of probability](/_astro/risk-evaluation-matrix-3.DVOFQ7Zo_Z1NN9TI.webp)

![The definition of damage](/_astro/risk-evaluation-matrix-4.DWqHbkpV_1EICSG.webp)

## The colours

[Section titled “The colours”](#the-colours)

Each risk value carries a colour, which indicates the severity and therefore the priority for action.

Colour

Severity

**Blue**

very low

**Green**

low

**Yellow**

medium

**Orange**

high

**Red**

very high

The full legend, with the corresponding values and intervention priorities, is available by hovering the question mark icon next to **Risk matrix**.

![The definition of the risk values](/_astro/risk-evaluation-matrix-6.CsyXN-WU_Z1p520R.webp)

## The three values in the risks list

[Section titled “The three values in the risks list”](#the-three-values-in-the-risks-list)

Value

Meaning

**Initial risk**

before the mitigation actions

**Variation**

the effect of the actions

**Final risk**

the residual risk, after the actions

All three are 0 for a risk that has been entered but not assessed.

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