Risk Matrix Calculator

This calculator uses the standard 5×5 grid with explicit bands — 1–4 low, 5–9 medium, 10–15 high, 16–25 very high — and it tells you the action each band requires, not just the colour. Move the two selects, watch the grid light up, and use the anchor guide below to keep every document on the site scoring the same way.

How to use the tool

1. Select the likelihood — 1 (rare) to 5 (almost certain) — using the anchors: the definition, not the feeling
2. Select the consequence — 1 (negligible) to 5 (catastrophic) — on the same anchored scale
3. Read the score and the band; the tool highlights the cell and writes the action the band requires
4. If the band is high or very high, add a control and re-score to see the drop — that drop is your justification for the control
5. Copy the anchor definitions into your site method statement, so every assessor on the site scores the same hazard the same way

Worked example

A forklift working a pedestrian corridor: likelihood 4 (it happens every shift — almost certain), consequence 4 (serious injury). Score 16: very high. Add segregation — a physical barrier, a one-way route, a pedestrian gate. Re-score: likelihood 2, consequence 4 — score 8, medium. The assessment now reads: risk reduced from 16 to 8 by barrier and route segregation; the residual 8 is managed by speed control and the daily inspection. That is a risk assessment an auditor can follow, and an investigator will thank you for after the event.

Standard & legal context

The 5×5 matrix appears in the HSE (UK) ACoP L80 on managing health and safety, in the ISO 31000 risk management guidance, and in most national frameworks. The grid itself is a convention, but the bands and the required actions are not optional — a matrix without consequences is a decoration. OSHA does not mandate a specific grid, but its enforcement practice expects a documented risk evaluation with the same logic. Whatever framework you follow, write the anchors down: 4 = serious injury, medical admission is a rule; 4 = bad is not.

Common mistakes

1. Scoring after the controls and calling it pre-control — pre-control score first, controls second, residual last, in that order
2. Treating a 9 and a 10 as the same medium — the band boundary is the decision point, and 10 means a date and an owner
3. Letting different assessors use different anchors — two people, two matrices, zero comparability
4. Re-scoring optimistically without adding a control — the residual must be earned by something physical, procedural or trained