How Many Fire Extinguishers Do I Need? | UK Guide 2026
- Harry poole
- Aug 20
- 5 min read
Introduction
The number of fire extinguishers required in a premises depends on more than just floor area.
In the UK, extinguisher provision should be based on the fire risks present, the size and layout of each storey, the fire ratings of the extinguishers, travel distances, and the findings of the fire risk assessment.
For general Class A risks, BS 5306-8:2023 provides guidance on minimum extinguisher provision and required fire ratings.
This guide explains the basic calculation and the other factors that can affect the final number of extinguishers required.
Start With the Class A Requirement
Class A fires involve ordinary combustible materials such as:
Wood • Paper • Cardboard • Textiles • Furniture
For many commercial premises, Class A provision provides the starting point for calculating the basic extinguisher requirement.
Storeys Up to 50m²
For a storey with a floor area of 50m² or less, the current guidance allows:
At least 1 Class A extinguisher
with a:
Minimum total Class A fire rating of 26A
Storeys Over 50m²
For storeys larger than 50m², the required Class A fire rating can be calculated using:
Floor Area (m²) × 0.065
A minimum of:
2 extinguishers
should be provided, with a combined Class A rating of at least:
26A
So even where the calculation produces a figure below 26A, the minimum provision still applies.
Worked Examples
200m² Floor
200 × 0.065 = 13A
However, the minimum provision still applies.
Minimum required: 26A across at least two extinguishers
400m² Floor
400 × 0.065 = 26A
Minimum required: 26A
with at least two extinguishers.
600m² Floor
600 × 0.065 = 39A
Minimum required Class A rating: 39A
The combined ratings of the extinguishers should meet or exceed this figure.
800m² Floor
800 × 0.065 = 52A
Minimum required Class A rating: 52A
1,000m² Floor
1,000 × 0.065 = 65A
Minimum required Class A rating: 65A
Why Fire Rating Matters
Extinguisher provision isn't based purely on the number of cylinders.
Each extinguisher carries a fire rating showing its tested fire-fighting performance.
For example:
Two 13A extinguishers = 26A combined
while:
Two 34A extinguishers = 68A combined
This means higher-rated extinguishers can provide greater Class A coverage.
However, a higher fire rating does not automatically mean fewer extinguishers can always be installed, because minimum quantities, positioning, and travel distance requirements still apply.
Travel Distance Matters Too
Having enough combined fire rating is only part of the calculation.
For a Class A risk, the maximum travel distance to an extinguisher is:
30 metres
This is the route someone would actually need to travel to reach the extinguisher — not simply a straight-line measurement across the room.
If the required travel distance cannot be achieved, additional extinguishers may be needed even if the total Class A rating is already sufficient.
What About Doors?
Where someone has to open a door to reach the nearest extinguisher, the permitted travel distance should be reduced by:
5 metres for each door
Someone should also not normally need to pass through a card or keypad-controlled security door to obtain an extinguisher.
The extinguisher should be positioned on the fire-risk side of that security door.
Other Fire Risks Need Separate Consideration
The Class A calculation provides the starting point for ordinary combustible materials.
It does not automatically determine the complete extinguisher provision for the building.
Additional or different extinguishers may be required where other hazards are present.
Class B — Flammable Liquids
Class B risks include substances such as:
Petrol • Diesel • Paint • Solvents
These risks require appropriate Class B-rated extinguisher provision.
Maximum travel distance is generally:
10 metres
Class F — Cooking Oils & Fats
Commercial kitchens and other areas containing significant quantities of hot cooking oil need appropriately rated Class F protection.
Maximum travel distance is generally:
10 metres
Electrical Equipment
Electrical equipment isn't itself a UK fire class, but the extinguishing medium must be appropriate where live electrical equipment may be involved.
For general electrical risks, suitable provision may be distributed throughout the premises.
For specific electrical hazards, such as:
Switchgear • Mains intake equipment • Distribution boards • Dedicated electrical plant
a dedicated suitable extinguisher may be required closer to the risk.
CO₂ or another appropriate electrically non-conductive extinguishing medium may still be suitable for these dedicated electrical risks.
Class C — Flammable Gases
Class C risks are assessed differently.
Portable extinguishers are not normally selected simply using a fixed travel-distance or floor-area calculation.
Where safe, the priority is generally to isolate the gas supply.
Specialist assessment may be required.
Class D — Combustible Metals
Class D fires involving combustible metals require specialist consideration.
The correct extinguisher can depend on the specific metal involved, so these hazards should be assessed individually.
Where Should Fire Extinguishers Be Positioned?
Extinguishers should be:
Clearly visible
Readily accessible
Positioned on or near escape routes
Near appropriate exits or specific fire risks
Free from obstruction
They should be located where a person can safely access them without travelling deeper into a fire risk.
How High Should Fire Extinguishers Be Mounted?
Portable fire extinguishers are normally mounted on a wall bracket, stand, or suitable cabinet.
As a general rule:
Smaller extinguishers up to 4kg total mass: carrying handle approximately 1.5m from the floor
Larger extinguishers: carrying handle approximately 1m from the floor
The extinguisher should remain easy to identify and remove safely.
What About Homes?
Domestic properties are different from commercial premises.
There isn't a simple rule that every private home must have a set number of portable fire extinguishers.
Domestic fire safety usually places greater emphasis on:
Smoke and heat alarms
Safe escape
Fire doors where required
Appropriate fire blankets or extinguishers where justified by the risk
Blocks of flats and converted properties can also have separate requirements for communal areas, which should be determined by the fire risk assessment and the building's fire strategy.
How Many Zenova FX Extinguishers Do I Need?
Zenova FX extinguishers have different Class A fire ratings, so the model selected affects the aggregate Class A provision.
For example:
FX500 — 3AFX2L — 13AFX6L — 34AFX9L — 43A
That means, for example, two FX2L extinguishers provide:
26A combined
while two FX6L extinguishers provide:
68A combined
But the correct combination still depends on:
Floor area
Minimum extinguisher quantities
Travel distances
Fire risks present
The fire risk assessment
So don't simply divide the required rating by the rating of one extinguisher and assume that gives the final quantity.
Example: 600m² Office Floor
A 600m² storey gives:
600 × 0.065 = 39A
The extinguishers selected need to provide at least 39A combined Class A rating, while also meeting the minimum quantity and travel-distance requirements.
If electrical equipment or other specific risks are present, additional suitable provision may also be necessary.
Regular Inspection and Maintenance
Once extinguishers are installed, they need to remain serviceable and accessible.
Good practice includes:
Monthly Visual Checks
Check that extinguishers are:
In the correct position
Visible and unobstructed
Not obviously damaged
Not discharged or tampered with
Showing the correct pressure where a gauge is fitted
Annual Servicing
Portable fire extinguishers should normally receive a basic service at least annually by a competent person.
Additional extended servicing or overhaul requirements depend on the extinguisher type.
Not Sure How Many You Need?
Every premises is different.
Floor area gives a useful starting point, but the final provision depends on:
Fire ratings • Layout • Travel distances • Doors • Fire risks • Electrical hazards • Cooking risks • The fire risk assessment
If you're unsure, we can help you identify suitable extinguisher types, ratings, and quantities for your premises.
Important Information
This guide provides general information based on the principles of BS 5306-8:2023 and should not be treated as a substitute for a suitable and sufficient fire risk assessment or site-specific extinguisher installation assessment.
The final number, type, rating, and position of fire extinguishers should reflect the individual premises and risks present.
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