How to Read a Bill of Quantities

Published 2026-07-26 • Structmate

A Bill of Quantities looks like a spreadsheet with a lot of rows. Once you know what each part is doing, it reads quickly — and more importantly, you can spot the parts that will cost you money if you skim past them.

The structure

A bill is normally divided into sections that follow trade order, roughly in the sequence the work happens: preliminaries, demolition and site preparation, excavation, concrete, masonry, structural steel, carpentry, roofing, windows and doors, internal linings, finishes, fixtures, services, and external works.

Each section contains items. Each item is one measurable piece of work with a description, a unit, a quantity, and empty columns for your rate and total.

The columns

Column	What it means
Item / code	A reference so the item can be cited in correspondence and claims
Description	What the work is, in enough detail to price it
Unit	How it is measured — see below
Quantity	How much there is
Rate	Blank. You fill this in
Amount	Quantity multiplied by your rate

Units you'll see

m³ — cubic metres. Volume: concrete, excavation, fill
m² — square metres. Area: brickwork, plasterboard, roofing, floor finishes
m — linear metres. Length: skirting, kerbs, pipework, edge beams
No. or Ea — number or each. Countable items: doors, windows, fixtures
t — tonnes. Usually reinforcement and structural steel
Item — a lump sum, not measured by dimension
Sum — a stated amount carried forward, common in preliminaries

Preliminaries

Preliminaries are project-wide costs that are not attached to a specific trade: site establishment, fencing, scaffolding, site sheds, temporary power and water, cranes, supervision, insurances, cleaning, and the cost of simply being on site for the duration. On a residential project these commonly run at 8 to 15 per cent of construction cost.

This is the single most common place builders lose money. Preliminaries feel like overhead and get compressed when a tender is tight, but they are real costs that continue every week the job runs. If your programme extends, preliminaries extend with it.

Provisional sums and PC items

A provisional sum is an allowance for work that cannot yet be measured properly — often because the design is incomplete. It gets adjusted to actual cost when the scope becomes clear.

A prime cost (PC) item is an allowance for a specific product that has not been selected yet — the classic examples being tapware, appliances and floor tiles. The supply cost is an allowance; the installation is normally measured separately.

Both are legitimate. Both are also where budgets quietly break, because clients tend to hear the total as fixed while the allowances are anything but. There is more detail here.

Five things to check before you price

The exclusions schedule. Read it first, not last. What is not in the bill is more dangerous than what is.
The assumptions. Every bill rests on assumptions where drawings were unclear. If one is wrong for your job, the quantity behind it is wrong too.
The drawing register. Confirm the bill was measured from the same revision you are pricing. Measuring Rev C and tendering Rev E is a real and expensive mistake.
Provisional sums and PC items. Total them up. If they add to a large share of the contract, the price is far less fixed than it appears.
Preliminaries against your programme. Check the allowance reflects how long you actually expect to be on site.

Then price it

Work through trade by trade, applying your own rates. Where a quantity looks wrong against your instinct, check it rather than overriding it — instinct is usually right about magnitude and wrong about detail. If it still looks wrong after checking, raise it. A quantity surveyor would far rather answer that question before tender than after award.