Fire Extinguisher Calculator

How many extinguishers and which types, by the BS 5306-8 method. A CO2 beside every water or foam, because nearly everything in a modern premises is electrical.

Built on BS 5306-8, the code of practice for selecting and positioning portable extinguishers. Your fire risk assessment sets the final number.

Premises type

Total floor area (m²)

Number of floors

Specific risks present

Commercial kitchen with cooking oilsElectrical equipment on site (computers, tills, printers, plant). Nearly every premises.Class B flammable liquid storage (fuels, solvents, paint)Class D combustible metals (magnesium, lithium, sodium)

How this works

BS 5306-8 gives a simple sum for ordinary risk premises. Multiply the floor area in square metres by 0.065 and that is the Class A rating you need on that floor. A standard water or foam extinguisher is rated 13A. Never fewer than two on a floor. Nobody walks more than 30 m to reach one.

Then the special risks. A CO2 beside every water or foam because almost everything in a modern premises is electrical. A wet chemical within 10 m of any cooking oil. Foam by any flammable liquid store. Specialist powder for burning metals.

What the sum cannot do is see your building. Long corridors, locked doors, racked storage and awkward layouts all add units the area alone does not. That is why the fire risk assessment sets the final number and the tool only gets you to the right conversation.