How is fire risk calculated?

Fire risk is calculated as Likelihood of fire x Consequence of fire. Both are scored 1-5. The resulting risk score (1-25) is categorised as Trivial, Tolerable, Moderate, Substantial or Intolerable. This method is used in PAS 79 fire risk assessments required under the Regulatory Reform (Fire Safety) Order 2005.

Who needs a fire risk assessment?

Every non-domestic premises and the common parts of residential buildings require a fire risk assessment under the Fire Safety Order 2005. The 'responsible person' (usually the employer, building owner or managing agent) must ensure a suitable and sufficient assessment is carried out and reviewed regularly.

How often should a fire risk assessment be reviewed?

There is no fixed legal interval, but best practice (PAS 79) recommends: annually for most premises, every 6 months for higher-risk buildings (HMOs, care homes), and immediately after any significant change, fire incident or near-miss. The review frequency should match the risk rating.

PAS 79 is the published standard for fire risk assessment methodology in the UK. It provides a structured approach for identifying fire hazards, evaluating risk and recommending remedial actions. PAS 79-1 covers housing and PAS 79-2 covers non-housing premises.

Can I do my own fire risk assessment?

For simple, low-risk premises the responsible person can carry out their own assessment using government guidance. For complex, high-risk or sleeping-risk premises (HMOs, care homes, large commercial), a competent fire risk assessor should be engaged. Competence schemes include BAFE SP205 and IFE registration.

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Fire Risk Score Calculator

Calculate a fire risk score using the likelihood x consequence matrix method per PAS 79 fire risk assessment methodology. Determine risk rating and review frequency.

Ignition Sources

Electrical, cooking, smoking, heating

Combustible Materials

Storage, furnishings, building materials

Occupant Vulnerability

Age, mobility, familiarity

Escape Route Adequacy

Quality and availability of escape

Fire Detection

Fire alarm and detection provision

Fire Protection

Physical fire protection measures

How We Calculate This

This calculator uses the standard risk matrix method from PAS 79 fire risk assessment.

The formula

Risk = Likelihood × Consequence (adjusted for mitigation)

Likelihood: based on ignition sources and combustible materials
Consequence: based on occupant vulnerability and escape provision
Mitigation: fire detection and protection reduce consequence
Score 1-4: Tolerable, 5-9: Moderate, 10-14: Substantial, 15+: Intolerable

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.