Someone building a house is usually handed a quote: a few lines and a total. A bill of quantities is a different kind of document, and the difference only becomes visible about four months in, when you want to know whether you are still on budget.
A quote tells you a price. A BQ tells you what the price was for.
3 to a contractor's quote, 4 to a bill of quantities. Counted from the rows below, and the count is not the decision.
What it costs to get
A contractor's quote
Free. Contractors provide them to win work.
A bill of quantities
A QS fee, paid before anything is built.
Level of detail
A contractor's quote
Often a handful of lines and a total.
A bill of quantities
Every element measured, with a quantity and a rate.
Comparing two contractors
A contractor's quote
You are comparing different assumptions, not different prices.
A bill of quantities
Same quantities, so the difference is genuinely the rates.
Knowing mid-build whether you are on budget
A contractor's quote
Not possible. There is no baseline to measure against.
A bill of quantities
Consumption compared to measured quantities, element by element.
Valuing a change
A contractor's quote
Negotiated from scratch each time.
A bill of quantities
Priced against existing rates.
Speed to start
A contractor's quote
Immediate.
A bill of quantities
Weeks of measurement first.
Small or simple jobs
A contractor's quote
Proportionate.
A bill of quantities
Overkill. The fee can exceed what it saves.
For a small, single-trade job, take the quote. A measured bill for a boundary wall costs more than it can possibly save.
For a house, pay for the measurement. The fee feels like money spent before anything is built, which is exactly why people skip it, and skipping it is how a build ends with no way to answer "are we over?" until the answer is yes. The BQ is not really a tendering document; it is the baseline that makes every later question answerable.
The middle path, if the fee is genuinely out of reach: ask the contractor to break their quote into measured elements with quantities and rates, and keep that breakdown. It is not a QS's bill and it carries the contractor's own assumptions. But it gives you something to measure against, which is infinitely more than a single total does.
A bill of quantities is not a document you produce to get a price and then file. It's the only thing that lets you know, mid-build, whether you are still on budget.
No single change breaks a build's budget. Fourteen of them, none written down, agreed verbally on site by whoever was standing there, is how it goes.
Most material loss on a build isn't theft. It's waste, over-ordering and deliveries nobody counted, which is why locking the store rarely fixes it.