BAL Calculator

To assist in your planning we have provided a BAL Method 1 Calculator to enable you to make a preliminary assessment of your property. This should be used as a guide only; the assessment of bushfire risk has many components that only experienced assessors are able to apply for an accurate risk assessment of your property.

Unsure what a BAL is and why it is important to you? Read more here.

Factors that influence the assessment of bushfire hazards include topography, vegetation type, weather, and local knowledge, which can be used to develop an understanding of likely bushfire behaviour.

Click here to start using the BAL Calculator.

According to AS3959-2009 the Method 1 BAL assessment is based on the following steps:

  1. Determine the relevant Fire Danger Index (FDI) – For all of Western Australia we utilise FDI 80;
  2. Determine the classified vegetation type(s) within 100 metres of the site ;
  3. Determine the effective slope under the classified vegetation type(s);
  4. Determine the distance of the site, building or building envelope from the classified vegetation type(s);
  5. Determine the BAL based on the above assessments using Table 2.4.3 from AS3959-2009; and
  6. Determine the appropriate construction standard for the proposed building or site.

1 Vegetation

We have provided some guiding images and a brief description to assist in classifying your vegetation. The images below are not definitive but allow the general public to formulate some guidance with respect to BAL ratings.


  • Mature vegetation 10-30m high. Typically dominated by Eucalypts.
  • Understorey consists of; small trees, tall scrubs, tall shrubs and vegetation that has dense, hard foliage.
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  • Mature vegetation 2-30m high. Typically dominated by Eucalypts and Acacias.
  • Understory consists of; grasses or low shrubs
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Mature vegetation

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Mature vegetation >2m high. Often a mixed species composition. Typical of coastal wetlands and tall heaths.

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Found in vary limited areas of Western Australia between the Esperance Plains, Avon Wheatbelt and Coolgardie (REF). Sparse multi-stemmed vegetation, with an understory of low shrubs and/or sparse grasses.

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Managed/Cultivated Gardens, Managed Parklands

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2 Slope

To use the Method 1 calculator you need to estimate the effective slope under the classified vegetation.

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3 Distance to Vegetation

Enter the number of metres (0-99) to the nearest classified vegetation.

(A number between 0 and 99 must be input and then press the enter key)

Service Areas