Fire Extinguisher Calculator

An indicative provision schedule based on BS 5306-8 baseline figures for portable fire extinguisher selection and installation. Output is a starting point for discussion with a competent surveyor, not a finished specification.

Methodology drawn from BS 5306-8: Fire extinguishing installations and equipment on premises — Selection and positioning of portable fire extinguishers — Code of practice.

Premises type

Total floor area (m²)

Number of floors

Class A fire load

Low: typical office, modern retail. Medium: storage, archives, paper-heavy environments. High: warehousing, racked storage, significant combustible materials.

Specific risks present

Commercial kitchen with cooking oilsSignificant electrical equipment (server room, switch room, plant room)Class B flammable liquid storage (fuels, solvents, paint)Class D combustible metals (magnesium, lithium, sodium)

How this works

BS 5306-8 sets a baseline of 26A of Class A coverage per 200 m² for low fire load environments, with proportional uplifts for medium and high fire loads. A standard 9-litre water or foam extinguisher provides 13A; the calculator translates total rating required into unit count, then applies the BS 5306-8 minimum of two Class A units per floor regardless of area.

Specific class additions are layered on top: Class F wet chemical within 10m of any commercial cooking, CO2 near electrical concentrations, foam for flammable liquids, specialist powder for combustible metals. The calculator does not account for layout obstructions, sightlines, the 30m and 10m maximum travel distance rules in practice (which depend on the specific room layout), or fire-resistance considerations — these are part of a competent survey and cannot be computed from the inputs here.