A quantity surveyor is a professional working within the construction industry concerned with building costs.

The profession is one that provides a qualification gained following formal education, specific training and experience that provides a general set of skills that are then applied to a diverse variety of problems. Predominantly these relate to costs and contracts on construction projects.

There are around 75,000 professional QSs working in the UK.
The profession developed during the 19th century from the earlier "measurer", a specialist tradesman

Tradesman

This article is about the skilled manual worker meaning of the term; for other uses see Tradesperson .A tradesman is a skilled manual worker in a particular trade or craft. Economically and socially, a tradesman's status is considered between a laborer and a professional, with a high degree of both...

 (often a guild

Guild

A guild is an association of craftsmen in a particular trade. The earliest types of guild were formed as confraternities of workers. They were organized in a manner something between a trade union, a cartel, and a secret society...

 member), who prepared standardised schedules for a building project in which all of the construction materials, labour activities and the like were quantified, and against which competing builders could submit priced tenders.