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Fire Extinguisher Rating Requirement Calculator

Work out fire extinguisher rating requirement instantly with clear inputs, formula shown and shareable results.

About Fire Extinguisher Rating Requirement Calculator

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.

Formulas

Area rule

Units = ceil(floor area / area covered per extinguisher)

Travel rule

Units = ceil(floor area / (pi x travel limit²)), minimum two per floor

Worked example

With the default values below, Fire Extinguisher Rating Requirement Calculator returns Extinguishers required of 3. Change any input above and every figure here is recalculated in your browser.

Inputs used

Floor areaminimum 1 m²
600 m²
Area covered per extinguisherminimum 10 m²
200 m²
Minimum class A rating per unitminimum 1 A
13 A
Maximum travel distance to an extinguisherminimum 1 m
20 m

Results

Extinguishers required
3
Total class A rating provided
39 A
Area per extinguisher achieved
200.0 m²
Coverage radius implied
20.0 m

Step by step

  1. 1Values used
  2. 2Area rule
  3. 3Travel rule
  4. 4Extinguishers required= 3
  5. 5Total class A rating provided= 39 A
  6. 6Area per extinguisher achieved= 200.0 m²
  7. 7Coverage radius implied= 20.0 m

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Preliminary estimate only. Extinguisher type, rating and siting must follow the applicable standard and a competent fire risk assessment.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Preliminary estimate only. Extinguisher type, rating and siting must follow the applicable standard and a competent fire risk assessment.

Frequently Asked Questions

How is the Fire Extinguisher Rating Requirement figure worked out?

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.

Does a bigger extinguisher reduce the count?

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.

What values do I need to enter?

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.

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