- A BOQ turns drawings and specs into items that can be priced and measured.
- Item description and unit of measure matter as much as the quantity.
- Take-off errors resurface later as variations, claims and delays.
- Checking the BOQ against approved drawings before pricing saves a lot.
A bill of quantities (BOQ) turns drawings and specifications into a list of defined items, each with a description, unit of measure and quantity. Contractors price on it, bids are compared on it, and interim payments are made against it during construction. Its accuracy affects the project from the first quotation to final handover.
What a BOQ contains
- Item number: grouped by trade section (civil, architectural, electrical, mechanical…).
- Description: exactly what is included — supply, installation, testing, finishing — with a reference to the specification.
- Unit of measure: cubic metre, square metre, linear metre, number, lump sum.
- Quantity: measured from the drawings using an agreed method of measurement.
- Unit rate and total: filled in by the contractor in the bid.
How a BOQ is prepared
Preparation starts with reviewing the drawings and specifications and clarifying any conflicts between them. Each element is then measured using consistent rules: where measurement starts, what is deducted for openings, and how overlaps are treated. Items are written with clear descriptions that cover the whole work without overlapping, and quantities are checked independently before issue.
A vague item is more dangerous than a wrong quantity: quantities are corrected by measurement, but vagueness becomes a dispute.
Why the BOQ decides your project's success
Cost
Under-measured quantities mean the owner pays more than expected through variations; over-measured ones mean inflated bids. A contractor pricing an incomplete BOQ may end up building work they never priced.
Schedule
Quantities drive duration and resource estimates. An error in concrete or services quantities feeds straight into labour and procurement planning.
Payments and claims
During construction, completed work is measured against BOQ items. A clear description and the right unit make monthly measurement straightforward and agreed; vagueness opens the door to disputes and claims.
Common BOQ mistakes
- Items duplicated across sections, or work no item covers.
- Unsuitable units, such as lump sum for measurable work.
- Descriptions that don't reference the specification or required tests.
- Quantities taken from out-of-date drawings.
The technical office's role
Our technical office prepares BOQs for owners before tender, reviews them for contractors before pricing to catch gaps and conflicts, and updates them during construction with every drawing revision. That early review costs far less than resolving disputes once work has started.
FAQ
What's the difference between a BOQ and a rate analysis?
The BOQ defines what is to be built and how much; a rate analysis breaks down each item's cost into materials, labour, equipment and overheads.
Who usually prepares the BOQ?
The consultant or the owner's technical office prepares it before tender; the contractor reviews it before pricing; it's updated during construction when drawings change.
Can BOQ quantities change after signing?
In remeasurement contracts, work is paid on quantities actually executed, and scope changes go through variation orders under the contract terms.
Engineers and specialists in government tenders, technical office, MEP and central HVAC, with more than 15 years in the Saudi market.
