Last edited 30 Jul 2019

Measured quantity

Quantity is a measurement of a physical entity in units that depend on the nature of that entity. Therefore, quantity indicates how much of something exists, existed or will exist.

In construction, ‘measured quantities’ typically form part of a bill of quantities (BoQ) and indicate how much of something will be required to construct a building or part of a building.

Usually prepared by a quantity surveyor (QS), the BoQ provides project-specific, measured quantities of the items of work identified by the drawings and specifications (which form part of the tender documentation). For example, in a traditional building, the BoQ will contain measured quantities for each item that goes to make up the final construction e.g bricks, doors, ironmongery, floor tiles, roof slates, etc. This means that potential tenderers know exactly how much of a given quantity will be required for the work and so they can price for it. This creates a level playing field as all tenderers are pricing for the same measured quantities which allows the client to make easy comparisons between the bids.

Measured quantities are typically expressed in number (e.g door handles), length (e.g handrails, kerbs), area (e.g floor tiles, plaster), volume (e.g concrete) or weight (e.g gravel).

When prices have been entered by a tenderer beside each measured quantity in a BoQ, this constitutes the tenderer’s offer.

Not providing measured quantities would require that the various tenderers on a project ‘take off’ the quantities themselves. With numerous tenderers with possibly different methodologies, as well as human error creeping in, the quantities taken off would vary, thus making the client’s job in comparing the tenders that much harder.

The New Rules of Measurement (NRM) are published by the Royal Institutution of Chartered Surveyors' (RICS) Quantity Surveying and Construction Professional Group. They provide a standard set of measurement rules for estimating, cost planning, procurement and whole-life costing for construction projects. Adopting a standard methodology such as NRM facilitates consistency and benchmarking and helps avoid disputes.

NRM is a suite of documents, comprising three volumes; NRM1, NRM2 and NRM3.

Fore more information see: New rules of measurement.

In some circumstances, it may be difficult to determine exact quantities, for example early in the development of a project. In this case approximate quantities may be estimated. These should be accompanied by a schedule of the assumptions made in determining the approximate quantities.

For more information see: Approximate quantities.