Work out fire extinguisher rating requirement instantly with clear inputs, formula shown and shareable results.
Portable extinguisher provision is set by two independent tests: an area rule, commonly one unit per 200 square metres for ordinary hazard, and a travel distance rule that no occupant should walk more than about twenty metres to reach one. The larger of the two counts governs, with a minimum of two per storey.
Area rule
Units = ceil(floor area / area covered per extinguisher)
Travel rule
Units = ceil(floor area / (pi x travel limit²)), minimum two per floor
Preliminary estimate only. Extinguisher type, rating and siting must follow the applicable standard and a competent fire risk assessment.
Units = ceil(floor area / area covered per extinguisher). Portable extinguisher provision is set by two independent tests: an area rule, commonly one unit per 200 square metres for ordinary hazard, and a travel distance rule that no occupant should walk more than about twenty metres to reach one.
It raises the rating but not the coverage, because travel distance still governs. Two smaller units well placed beat one large unit in a corner.
This calculator takes 4 inputs: Floor area, Area covered per extinguisher, Minimum class A rating per unit, Maximum travel distance to an extinguisher. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.