Bill of quantities: how to read it, check it and compare quotes
A bill of quantities (BOQ) gathers the works of a construction project into a list of items, each with a description, a unit of measurement and a quantity, so that they can be priced on a common basis. Its value also lies in the details around the number: what the work includes, which documents it is based on and what still needs to be completed. This guide explains how to read the document and what to check before you pass it to contractors.
What every item in a bill of quantities should show
A line that holds only the name of a work and a quantity leaves the bidder a lot of room for interpretation. To understand what is being priced, read the description, the unit, the quantity and the reference to the relevant specification together. Details that are already in the project documents do not have to be written again in every line, but it must be clear which document, and which version of it, the item refers to.
| Field | What it shows | What to check |
|---|---|---|
| Number and description | Identifies the work and its scope | That the description tells different works apart and refers to the details needed |
| Unit of measurement | m², m³, m (linear metres), unit or lump sum | That the quantity and the price refer to the same unit |
| Quantity | The extent of the work on the chosen basis of measurement | Where the quantity comes from, and whether it is measured, estimated or still waiting to be completed |
| Price and amount | The unit price, multiplied by the quantity | That a missing price is not shown as work at no cost |
An example, for illustration only: two items can cover the same flooring area, but one includes the supply of the tiles and the other covers installation only. Comparing their prices without reading the descriptions shows a gap that is not necessarily a difference in the price of the same work. Waste removal, preparing the base and finishing details also need to be defined according to the documents and the agreed scope.
How to divide the work into chapters and packages
The structure should suit whoever is pricing and the way the project is run. For a main contractor, the chapters can be gathered in one tender document. When the client contracts separately with each trade, the work has to be divided into packages with clear boundaries between them. Check who supplies, who installs and who is responsible for the preparation works, to reduce overlaps and gaps between packages.
A breakdown by building, floor or flat is useful when you want to track different areas. Agree the level of detail in advance, based on the design available and the purpose of the document. With repeated flats you still need to check differences in type, area and upgrades: never copy a quantity from one flat to another without checking that it fits. A more detailed structure is shown in the guide to the construction BOQ.
The BOQs for electrical, plumbing and other building services may come from the consultants. When you gather them into one set, keep the identity and the version of each source, and agree who handles the interface between the building works BOQ and the services BOQs. Merging the files is not a professional review of the services design, and it does not change the consultant's responsibility for the content they prepared.
The difference between the document, the takeoff and the estimate
A quantity takeoff is the measuring and the breakdown behind the quantity. A bill of quantities arranges the works into items meant for a defined use, for example obtaining quotes. A cost estimate adds prices, based on a source and on assumptions that should be stated. So a list of quantities is not, in itself, an assessment of the construction cost.
A quantity for pricing and a quantity for ordering material are not always the same either. Pack sizes, cutting, waste and the method of measurement can change the quantity you need to order. Do not add one flat percentage to all materials without checking. The separation between these stages of the calculation is explained on the page about physical quantity, BOQ quantity and order quantity.
Checks before you send it out for quotes
- Design and versions: list the drawings, specifications and models used to prepare it, and make sure there is no unexplained mix of versions.
- Complete scope: check which chapters are included, which works are excluded and which details are waiting for the designer or a consultant.
- Duplicates and boundaries: look for works that appear in two chapters, and at the link between supply, installation and preparation.
- File structure: check the units, the totalling formulas and the cells for prices, and keep an identified copy of the version you sent.
- Assumptions and qualifications: ask the bidders to state changes, deviations and works they did not price, so that the quotes can be compared.
If a detail has not been decided yet, mark what is missing and what is needed to complete it. When you use an estimated quantity, say so, next to the basis of the estimate. That way whoever reads the document can tell a measured quantity from a decision that is still open.
How to handle a change after the BOQ is issued
When a new drawing arrives, keep the previous version and identify the items it affects. Record what changed in the quantity or the description, which document the update came from and when the new version was issued. A change in a description can matter even when the quantity stays the same. When you compare quotes, make sure all the bidders worked from the same version, and ask each of them explicitly whether the quote includes the update.
The document can support the review of changes and of the contractor's payment accounts, according to what was agreed in the project. On its own it does not approve a quantity built on site, or a payment. I am a registered building technician and quantity surveyor, and I agree the purpose of the service and the level of detail with the client in advance, based on the design material and the intended use.
Frequently asked questions
Who prepares the document?
A quantity surveyor is an engineer or a registered building technician, like Yaakov Avital, who prepares the BOQ for the building works from the documents and the agreed scope of service. The BOQs for building services need coordination with the relevant consultants. It is important to agree who is responsible for each part and for checking the interfaces between them.
Which files do you need to send?
A description of the project, the purpose of the work, up-to-date drawings and specifications, and a model if there is one and it is relevant. It helps to attach a list of versions and to state the breakdown you need. The detailed checklist is in the guide to BOQ preparation.
Are prices already included in the deliverable?
Not necessarily. I can prepare price columns for the bidders to fill in, or we can agree separately on a priced deliverable, with its price source and assumptions stated. Check what the quote for the service includes before the work starts.
Can I see a sample before ordering?
On the sample bill of quantities page you can download a generic BOQ to fill in, with no quantities, prices or identifying details, and see the structure of the chapters. A sample is meant to show the level of detail. The deliverable for a specific project depends on its scope, the design available and the needs agreed with the client.
Have a project? Tell me briefly what the project is and what already exists. When the project is a good fit, I usually reply with focused questions and a written quote.
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.