Three quantities for the same work: measurement, BOQ and order
Net quantity vs BOQ quantity vs order quantity: how much is in the design, how much appears in the bill of quantities (BOQ) and how much material has to be bought are three different questions. To use a quantity correctly, you need to know what it includes, which rule it was calculated by and what it is for. This guide explains how to keep the measurement, the basis for pricing and the order from the supplier apart.
Net quantity: measuring a defined part of the project
The net quantity, the physical quantity, describes a length, an area, a volume or a number of units taken from the design: for example, the surface area of one side of a wall, the volume of concrete in an element, or the number of doors on a floor. Even here a definition is needed. Does the area include the openings? Which layers were included in the volume? Which floor and which design revision does the measurement refer to?
Next to the result, state the unit, the location and the source. A measurement from a drawing requires checking the scale and the units; a figure from a model requires checking which elements and layers were included. When a new revision arrives, check which quantities changed. There is more in the guide to quantity takeoff from drawings and models.
BOQ quantity: the basis for pricing
In the bill of quantities, the quantity is measured according to the item description and the methods of measurement that apply to the project. Check the unit of payment, the scope included in the rate, and the rules for deducting openings or for separating works. A quantity for pricing can differ from the physical measurement without either of them being wrong. The difference must be explained.
Before comparing bids, make sure the bidders are pricing the same scope in the same unit. A price per m² cannot be compared with a price per unit without understanding the basis of the calculation. Even a price per m² can include preparing the substrate for one bidder and a narrower scope of work for another. The structure of the bill of quantities and the item descriptions are there to make that common basis clear.
Order quantity: fitting the material and the supply
The order quantity is derived from the work to be done and from the product chosen. Coverage rate, number of coats, cutting, overlaps, standard sizes and pack sizes can all affect it. Check the manufacturer's data and the working conditions; there is no fixed waste percentage that suits every material or every project.
For a flooring order, for example, you need to know which product was chosen for each flat, what the pack size is and how the work zones are divided. A total quantity for the building is not an order schedule for each flat. Record the measurement basis, the planned addition, the reason for it and the rounding to packs separately, so that every step can be checked.
A worked example of net quantity vs BOQ quantity: wall area and paint
Take one wall 5.00 m long and 2.80 m high. The window is 1.20 × 1.20 m and the door is 0.90 × 2.10 m. The dimensions and the rules in the example are assumptions for illustration only, not an instruction for measuring on a project.
| What is calculated | Calculation | Result |
|---|---|---|
| Gross wall area | 5.00 × 2.80 | 14.00 m² |
| Openings | 1.44 + 1.89 | 3.33 m² |
| Net physical area | 14.00 − 3.33 | 10.67 m² |
| Coverage basis for two coats | 10.67 × 2 | 21.34 m² of coats |
The quantity of the item for pricing is set by the agreed method of measurement. If, in the example, it was agreed to measure gross without deducting these openings, the BOQ quantity is 14.00 m². That is the assumption of the example, not a general deduction rule. So here, net quantity vs BOQ quantity is 10.67 m² against 14.00 m². To order the paint, divide the coverage basis by the product's relevant coverage rate, and check whether the manufacturer's figure refers to one coat or to the whole coating system. Then fit the result in litres to the pack sizes and the working conditions.
How to show the differences in the file
- Keep separate columns for the net quantity, the BOQ quantity and the order quantity, when they are part of the agreed deliverable.
- Keep the item code, the description and the unit, and break the quantities down by building, floor or flat as needed.
- Show the rule that leads from one quantity to the next, and the assumptions, instead of changing a number without explanation.
- Mark missing information for completion. An empty cell or a gap in the design is not permission to enter zero.
- Keep the date and the version, and mark the change against the previous measurement.
What to define before ordering a quantity takeoff
State whether the deliverable is for a tender, a budget, checking bids or procurement. Define the chapters and the breakdown you need by floor, by zone and by flat.
Yaakov Avital, a registered building technician and quantity surveyor, reviews the material and the scope before quoting. The list of documents for preparing a bill of quantities helps you prepare the request.
Frequently asked questions
Net quantity vs BOQ quantity: which one is correct?
Both can be correct at the same time. The net quantity measures the design; the BOQ quantity follows the agreed method of measurement. The difference must be explained, as in the wall example: 10.67 m² against 14.00 m².
Can material be ordered straight from the BOQ quantity?
Only after checking that the quantity represents the order basis that the product and the work require. The scope of an item for pricing is not necessarily the scope of an order from a supplier.
Does a gap between two quantities mean a mistake?
Not necessarily. First check that the purpose, the unit, the scope and the version are the same. When the basis is the same and the gap remains, record it and find out why.
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Contact me for a quote* Created with AI for marketing, for illustration only. Not reviewed by Yaakov Avital and not professional advice. Every project must be checked on its own by a professional quantity surveyor and an engineer.