How to Read a Bill of Quantities (BOQ): A Guide for Building Owners

A bill of quantities (BOQ) lists every measurable item of work in a construction project, with its quantity, unit, rate and amount. It is the bridge between drawings and money — and the best tool an owner has for understanding, comparing and controlling construction cost.

The anatomy of a BOQ line

Item	Description	Qty	Unit	Rate	Amount
3.04	Reinforced cement concrete in columns, specified mix, including formwork, placing, compacting and curing	85	m³	—	—

• Description — defines exactly what the rate includes. This is where disputes are won or lost.
• Quantity — measured from the drawings using agreed measurement rules.
• Unit — m³, m², kg, tonne, nos, or lump sum (LS).
• Rate — the price per unit, including labour, materials, plant and overheads unless stated otherwise.
• Amount — quantity × rate.

How BOQs are organised

Most BOQs are grouped into sections that follow the construction sequence: preliminaries, earthwork, piling, concrete work, reinforcement, structural steel, masonry, finishes, doors and windows, plumbing, electrical, and external works. A summary sheet totals each section.

What to check as an owner

Descriptions match the specification

If the specification calls for a certain concrete strength or rebar grade, the BOQ description should say so. A vague description allows a lower-cost substitute.

Quantities are reasonable

Simple ratios help spot errors. For example, the weight of reinforcement per cubic metre of concrete, or steel weight per square metre of a PEB, should fall within a sensible range for the building type.

Provisional sums are identified

Items marked "provisional" are estimates for work not yet fully designed. A BOQ with many provisional sums carries more cost risk.

Exclusions are clear

Check what is excluded — utility connections, approvals, VAT, testing, temporary works. Exclusions are where "cheap" bids become expensive projects.

Comparing contractor bids

When every contractor prices the same BOQ, you can compare rates line by line instead of comparing only totals. Look for:

• Unusually low rates on high-quantity items — possible risk of claims or quality problems later.
• Front-loaded rates — high rates on early items (such as piling) to improve the contractor's cash flow.
• Arithmetic errors — they happen more often than you might expect.

Preliminary vs detailed BOQ

At early stages, a preliminary BOQ estimates key quantities from floor area and structure type using engineering consumption ratios. It is ideal for budgeting and comparing options. A detailed BOQ is measured from final drawings and is used for tendering and contracts.

EstimatrixBD produces a preliminary BOQ from a few inputs, and our Quick Budget Calculator gives a first budget range in seconds. When you are ready to tender, our team can prepare a detailed BOQ from your drawings — see our structural design and BOQ service.