A bill of quantities lists every item of work on a job, with a measured quantity against each one, so that every contractor bidding prices the same scope. Read from left to right it looks like a shopping list. The money is in the columns most people skim: the units, the provisional sums, and what the measure deliberately leaves out.
If you have been handed a bill and told to price it, this is what each part is doing and where the costs go missing.
What a bill of quantities is actually for
A bill of quantities turns a set of drawings into an itemised, measurable list of the work. Its job is comparison. When five contractors price the same bill, the returns can be compared line by line, and a number that is out by a factor of three stands out immediately.
That is the part worth understanding before you price one. The quantities have already been measured for you, which means you are not being asked how much work there is. You are being asked what you would charge to do it. Those are different questions, and confusing them is how contractors end up carrying someone else's measurement risk.
How the document is ordered
Most bills follow the same broad sequence:
- Preliminaries first, covering everything that is not a physical piece of work: site management, welfare, insurances, scaffolding, temporary services, plant
- Work sections in roughly construction order, from substructure up through frame, envelope, finishes and services
- Provisional sums and contingencies at the end, covering work that is known about but not yet designed
The ordering is not arbitrary. It follows a measurement standard, which in the UK is NRM2 and in Australia and New Zealand is ANZSMM. Both set out how each item must be described and measured, so a wall in one bill is measured the same way as a wall in another. The RICS new rules of measurement publish the UK rules in full.
The five columns and what each is really telling you
- Description — what the item is, in enough detail to price without guessing. If you find yourself guessing, that is a tender query, not a judgement call.
- Unit — m², m³, linear metre, tonne, number, or "item". The unit tells you how the risk sits, and it deserves more attention than it usually gets.
- Quantity — measured from the drawings, not estimated. Check whose measure it is.
- Rate — your price per unit, everything included. This is the only column you fill in.
- Total — quantity multiplied by rate.
One word in that list carries more risk than the rest. An item measured as "item" rather than a quantity is a lump sum, and a lump sum means you have absorbed the quantity risk yourself. If the drawing later shows more of it, that is your problem. Price those lines with the drawings open, never from experience.
Where a quantity actually comes from
Take a strip footing, 600 mm wide and 250 mm deep, running 48 m in total.
0.6 × 0.25 × 48 = 7.2 m³
That is the figure in the bill, and it is exactly right. It is also not what you will pour.
Measurement standards measure work net as fixed in place. The bill describes the footing, not the concrete that leaves the batching plant. Everything between those two numbers belongs in your rate:
- Over-dig, because no excavator leaves a trench exactly 600 mm wide
- An uneven formation soaking up depth you did not measure
- Concrete lost in the barrow, the pump line, and the last part-load
- Waste from the pour itself
Allow 5% and you are pouring roughly 7.56 m³ against a measured 7.2 m³. On one footing that difference is trivial. Across a substructure it is not, and it is entirely on you, because the quantity in the bill was never wrong.
Now the rate. Round figures below to show the shape of the build-up, not our rates — use your own:
- Ready-mix supply, £150 per m³
- Placing and compacting labour, £40 per m³
- Waste and over-dig at 5%, £9.50 per m³
- Sub-total £199.50 per m³
- Overhead and margin at 15%, £29.93
- Rate entered in the bill: £229.43 per m³
7.2 m³ at £229.43 is £1,651.90. The number in the bill is 7.2 either way. What separates a rate you can stand behind from one you hope is about right is whether the waste, the over-dig and the margin were built in deliberately or assumed to be somewhere in a rounded figure.
Provisional sums, prime cost sums and contingencies are not the same thing
This is where most of the money goes missing, because the three get read as one.
A provisional sum is an allowance for work that is known about but not designed well enough to measure. It will be replaced by a real price later. It is not your money and it is not your margin. If you add your percentage on top of a provisional sum without saying so, you have quietly inflated your tender against a competitor who did not.
A prime cost sum covers goods or services from a supplier the client will choose, typically specialist work. You are expected to price your attendance and profit on it separately, and those lines are usually right there below it. Leaving them blank gives away the money you were entitled to.
A contingency belongs to the client. It is there for the unknown, and it is not available to cover your underpricing.
Read all three as fixed prices and you will misread the tender total by whatever they add up to, which on a design-incomplete job can be a large share of the contract.
How to check a bill before you price it
- Do the preliminaries reflect the real programme length, or a shorter one?
- Are provisional and prime cost sums clearly marked, and have you kept your margin out of them?
- Is anything measured "item" that should carry a quantity?
- Are the quantities the client's, and does the contract make them yours once you sign?
- Does the specification contradict anything measured "as drawn"?
- Are there attendance and profit lines under every prime cost sum?
Anything unclear goes in as a tender query rather than being priced around. A qualification on the face of your bid is worth more than a low number you cannot defend when the job starts.
What if there is no bill?
On smaller projects there often is not one. A schedule of works is the usual alternative, typically two to six pages, where each item is priced as a lump rather than measured. It carries the essential information for pricing without the cost of a full measure, and the quantity risk sits with you rather than the client. Worth knowing which of the two you have been sent before you start.
Who works with bills of quantities
- Main contractors
- Subcontractors
- Developers
- Architects
- Quantity surveyors
FAQ
What is a bill of quantities? An itemised list of every piece of work on a project, with a measured quantity, unit and description against each item, prepared from the drawings. Contractors add rates to produce a tender price. Because everyone prices the same list, the returns can be compared like for like.
Who prepares a bill of quantities? Usually a quantity surveyor or cost consultant working for the client, so that the same document goes to every tenderer. Contractors sometimes commission their own for a job where the client has issued drawings only.
What does "item" mean in the unit column? That the work is priced as a lump sum rather than by a measured quantity. You carry the quantity risk on those lines, so price them from the drawings rather than from memory.
Is a bill of quantities the same as an estimate? No. A bill is the measured scope with no prices in it. An estimate is what a particular contractor would charge to do that scope. The same bill priced by five contractors produces five different estimates.
Are quantities in a bill guaranteed to be correct? That depends entirely on the contract. Some forms make the client responsible for the measure and remeasure on completion; others transfer it to you at signature. Check which before you rely on the numbers.
Do I need to allow for waste separately? Yes. Bills measure work net as fixed in place, so waste, over-dig and offcuts are never in the quantity. They belong in your rate.
Where to start
If you have been sent a bill and want a second pair of eyes before you commit a price to it, or you need one prepared from your own drawings, send the documents over and we will come back with a fixed fee and a turnaround date. We prepare fully measured bills of quantities and handle tender pricing where you would rather hand over the whole submission.