A quote is a fixed price the builder commits to; an estimate is an educated guess that can change. For anything more than a small job, you want a written quote — and you want at least three of them, broken down clearly enough to compare line by line.
Quote or estimate — why the word matters
Citizens Advice puts it simply: a quote is a fixed price, so you know what you're getting and what it will cost, while an estimate is just a rough guess, so you might end up paying more. Once you accept a quote it becomes a binding agreement, whether it's written down or not — but having it in writing is what lets you prove what was agreed if there's a dispute later. Some builders charge for quoting, particularly on complex jobs that need design work, so ask first.
What a proper quote includes
A good quote gives a fixed total price rather than a daily rate; a breakdown of all the work and the materials needed, with separate costs for each; how long the price is valid for; whether VAT is included; and the circumstances in which the price can go up. It should also make clear who is responsible for things like skip hire, waste removal, and applying for building regulations approval.
Watch the provisional sums
Builders' quotes often include 'provisional sums' or 'prime cost sums' — allowances for things not yet specified, such as £3,000 for a kitchen you haven't chosen or an allowance for groundwork nobody can price until the ground is opened up. They're legitimate, but they're where a fixed price quietly stops being fixed. Ask what each one covers, how the final figure will be worked out, and make sure they're realistic — an artificially low allowance makes a quote look cheaper than it is.
When the builder is allowed to charge more
Once you've accepted a quote, the builder can only charge more if you ask for extra work that wasn't included, if they tell you extra work is needed and you agree to pay for it, or if they made a genuine mistake writing down or calculating the price. Agree every change in writing, with a price, before the extra work starts — not in a conversation on site that nobody remembers the same way later.
Comparing quotes fairly
Give every builder the same written description of the job so you're comparing like with like. Then compare line by line, not just the totals. Be cautious of any quote far below the others: Citizens Advice notes it can mean the builder lacks the right skills or experience, isn't being honest, or isn't actually quoting for the same work.
Frequently Asked Questions
Can a builder charge more than the quote?
Only if you ask for extra work, agree to extra work they say is necessary, or they made a genuine error in calculating the original price. Otherwise the quoted price stands.
How many quotes should I get?
At least three written quotes, all based on the same description of the work, so the comparison is fair.
Is a verbal quote legally binding?
Accepting a quote creates a contract even if it's verbal, but proving what was said is hard. Always ask for it in writing before agreeing to anything.
Where this information comes from
General information only, not legal or financial advice. Last checked 2026-09-30.
