Bill of Quantities vs trade breakdown: which do you actually need?

Published 2026-07-26 • Structmate

Builders ask for a Bill of Quantities when what they need is a trade breakdown surprisingly often — and end up paying roughly twice as much for a document formatted for a purpose they do not have. The two are related but they answer different questions.

The difference in one line

A trade breakdown tells you how much of everything there is, organised by trade so you can get quotes. A Bill of Quantities does the same thing to a formal standard of measurement, itemised and structured so it can sit inside a contract.

Side by side

Choose a trade breakdown when

• You are pricing a residential job for a private client and there is no formal tender process
• You mainly need comparable quotes from subcontractors, quickly
• You are deciding whether a job is even worth bidding
• The contract will be a standard domestic building contract with a lump sum
• The project is under roughly $1.5 million

Choose a full Bill of Quantities when

• The tender documents require a priced bill returned with your submission
• The contract will be administered with progress claims assessed against measured quantities
• You expect variations to be contentious and want a measured baseline to argue from
• A superintendent, architect or quantity surveyor is administering the contract
• The project is larger, or the client is a developer or government body

The variations argument

This is where the extra cost of a full bill usually pays for itself, and it is the part builders underestimate. When a client claims something was always included and you say it was not, the argument is settled by what was measured. A properly itemised bill with an exclusions schedule turns a subjective dispute into a document check. A trade breakdown gives you far less to stand on.

If you have had a variation dispute in the last two years, weight that heavily. One avoided argument on one job typically exceeds the difference in fee across several.

A reasonable middle path

A pattern that works well for builders doing a mix of work: trade breakdowns as the default for everyday residential pricing, full bills reserved for tenders that require one, jobs above about $1.5 million, and any client you have reason to think will be difficult about scope.

If you are unsure on a specific job, send the drawings and say what you are pricing for. A straight recommendation costs nothing, and sometimes the answer is the cheaper service.

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