A quantity surveyor in Australia is a professional who specializes in assessing and estimating construction costs for building projects. They play a crucial role in ensuring that projects are delivered within budget by providing accurate cost advice at various stages of the project lifecycle. Quantity surveyors are responsible for preparing cost estimates, tender documents, and bills of quantities. They also assist in contract administration and help manage project finances. Their expertise helps clients and construction companies make informed decisions regarding the financial aspects of construction projects.