What Is a Bill of Quantities (BOQ) in Construction?

Ask ten contractors how they priced their last tender and most will describe the same starting point: a thick document of numbered lines, each with a description, a unit, a quantity and an empty rate column. That document is the bill of quantities, and in much of the world it is the single most important commercial document in a project after the contract itself.

This guide explains what a bill of quantities is, what goes into one, who prepares it, and how it is used once the job starts — from the first interim valuation to the final account.

What is a bill of quantities?

A bill of quantities (BOQ) is a document that itemises all the work required by a project, broken down into measurable items with a description, a unit of measurement, and a quantity. It is prepared by — or on behalf of — the client, and issued to tenderers so that every contractor prices exactly the same scope in exactly the same way.

The empty rate column is the point. When all bidders receive an identical bill, their totals can be compared directly, and any item can be interrogated later. Without a BOQ, a tender comparison becomes an exercise in guessing whether one contractor included scaffolding, or site clearance, or the cost of temporary power.

The terminology trap: BOQ, takeoff and schedule of values

These three terms get mixed up constantly, so it is worth separating them:

• Quantity takeoff — the measuring exercise itself. Someone (a quantity surveyor, estimator or the contractor) counts and calculates the quantities from the drawings. This is the raw material.
• Bill of quantities — the formatted document produced from that takeoff: numbered items, standard descriptions, units and quantities, issued for pricing. The dominant term in the UK, Ireland, the Gulf, Australia and much of the EU.
• Schedule of values — the American cousin. It splits the contract sum into payment buckets (usually by trade or phase) rather than by measured item, and exists mainly to support progress payments.

In the US you will more often hear quantity takeoff plus a schedule of values. In the UK and EU, the BOQ is a formal, often standard-form document. The underlying idea is identical: count the job, describe it consistently, and attach money to each part of it.

What goes into a bill of quantities?

A well-built BOQ is organised so that a pricing team can work through it methodically. It typically contains:

• Preamble and preliminaries — the rules of the game: what is included, how quantities were measured, what the contractor is expected to allow for (site setup, insurance, temporary works, cleaning).
• Measured works — the main body, grouped by trade or element: demolition, earthworks, concrete, masonry, roofing, joinery, mechanical, electrical, finishes, external works.
• Provisional sums — an allowance for work that cannot be measured yet, to be adjusted later against actual cost.
• Prime cost (PC) sums — an allowance for a specific item supplied at actual cost, plus a fixed percentage for the contractor's handling and profit.
• Daywork rates — agreed hourly rates for work that cannot be measured on a bill basis, used when instructed variations fall outside the priced items.

Each measured item usually follows the same six-column shape:

The tenderer fills in every rate and amount. Rates are usually expected to cover labour, material, plant, waste, overhead and profit for that item — the exact composition is defined in the preamble, not assumed.

Who prepares it, and when?

On larger projects the BOQ is produced by the client's quantity surveyor, working to a published measurement standard — NRM2 in the UK for building work, CESMM4 for civil engineering, or a national equivalent elsewhere in the EU. The drawings and specification drive the measuring, and the bill is usually issued with the tender documents.

On smaller projects there is often no formal BOQ at all. Instead the contractor measures the job themselves and prices it as a lump sum or a simple schedule of rates. That is a perfectly reasonable approach — but it moves the risk of an incomplete count from the client onto the contractor, which is worth remembering when a job starts to go sideways.

How a BOQ is used once work begins

The bill does not become irrelevant when the contract is signed. It quietly shapes the money for the rest of the project:

1. Tender comparison. Identical items mean totals can be compared, and outliers investigated item by item rather than argued over in aggregate.
2. The priced bill becomes the contract sum. The rates the contractor entered are the agreed rates.
3. Interim valuations. Monthly payment applications are built by measuring the work actually done and applying the BOQ rates to it — which is also why a priced bill makes valuations much faster.
4. Variations. When instructed work differs from the bill, the BOQ rates usually provide the first basis for pricing it. Disagreements tend to appear precisely where the bill had no comparable item.
5. Final account. At the end, remeasured quantities, provisional sums, PC sums and variations are reconciled against the original bill.

The mistakes that cost the most

Almost every BOQ dispute traces back to one of a handful of causes:

• Thin descriptions. "Concrete" is not a description. A missing strength class, thickness or reinforcement note leaves the rate open to interpretation — and interpretation always favours the person who wrote it.
• Inconsistent units. Mixing m² and m³ across comparable items makes the totals meaningless to compare.
• Missing preliminaries. If the preamble never states who provides site power, welfare or waste removal, every tenderer prices a different job.
• Quantities measured from superseded drawings. Revision control is not an administrative detail; a bill measured from the wrong revision misprices the whole project.
• No link between the bill and the site. This is the expensive one. The bill says 1,180 m² of blockwork; nobody notices until month four that 1,340 m² has actually been built.

Where the bill and the jobsite meet

That last mistake is the gap most teams struggle with. A BOQ is a forecast, and forecasts drift. The only way to catch the drift early is to track actual cost against the same items the bill was priced from.

A BOQ becomes your problem at tender stage, because you have to turn hundreds of measured lines into a single price and a programme. PlanoTrak does not do the measuring — but it does hold the priced result. A project can start life as an estimate: each task carries its own estimated cost, the project totals them, and the estimate can be exported as a PDF to send to the client. Approving it converts the estimate into a live project and sets that total as the official budget. From there the real expenses, materials, machinery and worker hours are logged against those same tasks, so the priced breakdown and what the site actually spends stay on one structure.

Two things it is not. It is not a replacement for your quantity surveyor, and it does not measure quantities from drawings — the bill has to be measured properly before any of this is worth anything. And the estimate it holds is your priced offer, not the client's bill: PlanoTrak stores the number you are quoting, not the measured schedule you quoted it from.

The Bottom Line

A bill of quantities turns a pile of drawings into a comparable, priceable, defensible list of work. Priced properly, it makes tendering fairer, valuations faster and variations less argumentative. But a bill is only as good as the loop that closes behind it: if nobody compares the priced quantity against the built quantity until the final account, the document has done half its job.