Australian Height Datum (AHD)
By George Giannakakis · M.Arch · RLA300580 · HIA Industry Judge
Last reviewed: · How we research
Australian Height Datum (AHD) explained in detail
The AHD is a vertical datum used for measuring elevations and heights above sea level in Australia. It is based on the mean sea level at a specific location, known as the 'benchmark', and is a reference point for sizeable interconnected drainage systems. Its primary use is for surveying, science, mapping, and civil engineering projects.
In this episode we explain what Bushfire Attack Level or “BAL” means. Tune in as we cover the different BAL ratings, how to find if your block is in a BAL zone, what the rough costs are and what you get for those costs as a result.
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Frequently Asked Questions
Common questions about australian height datum (ahd)
AHD (Australian Height Datum) is the official height reference used across Australia, set to the mean sea level. When you see a number like 'RL 32.450 AHD' on your survey, it means that point on your block is 32.45 metres above the AHD benchmark - not above your street or any local reference.
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