Quote or estimate: the difference that decides who pays for the overrun
Last reviewed 12 September 2026
The two words are used as though they mean the same thing. They do not, and the difference decides who absorbs it when the job costs more than the paper said.
This is the single most expensive piece of vocabulary in the trades. A document headed "quote" and a document headed "estimate" carry different legal weight in the United Kingdom, and most disputes about a final bill come down to which one was actually sent.
A quotation is an offer
A quotation is a firm offer to do defined work for a stated price. When the customer accepts it, an agreement is formed on those terms. You are then committed to that price for that scope, and if the work takes twice as long as you thought, the extra time is yours to absorb. The customer is committed too: they owe the quoted sum for the quoted work.
That is why the scope on a quotation matters more than the number. The price is only fixed against the work you actually described. Anything you did not describe is not in the price, which is precisely what your exclusions list is for.
An estimate is an informed opinion
An estimate is your best assessment of the likely cost, given honestly, and it does not bind you to that figure. It is useful early, when the scope is genuinely unclear, when access has not been seen, or when the customer wants a sense of the order of magnitude before committing to a survey.
It is not a licence to charge whatever you like afterwards. Where no price has been fixed, a consumer is only obliged to pay a reasonable price, under the Consumer Rights Act 2015. An estimate of 3,000 pounds followed by an invoice for 9,000 pounds will be very hard to defend, and a large unexplained overrun on a domestic job is a common complaint to trading standards.
The practical test
Ask yourself one question before you send anything: have I seen enough to be held to this number? If the answer is yes, send a quotation and price it properly. If the answer is no, send an estimate, say clearly that it is an estimate, and say what you would need to see in order to turn it into a fixed price.
Say which one it is, in the document
Courts and complaint handlers look at substance, not just the heading. A document called an estimate that reads like a firm offer with a precise figure and a start date can be treated as a quotation. So make it unambiguous in the body text, not just the title.
- On a quotation: "This is a fixed-price quotation for the work described. It is valid for 30 days from the date above."
- On an estimate: "This is an estimate, not a fixed price. It is based on what could be seen on the day and may change once the floor is lifted. We will confirm a fixed price before starting."
What turns an estimate into a bill nobody argues about
If you work on an estimate, the way to avoid a fight at the end is to remove the surprise. Tell the customer at the moment the cost changes, not on the invoice. A short message saying that the joists under the bay are gone, that it adds roughly a day and about 260 pounds of timber, and asking them to confirm before you carry on, converts a dispute into an approved variation.
Validity periods, and why every quote needs one
A quotation with no expiry date can be accepted months later, at a price built on material costs that have since moved. Thirty days is the normal working period for domestic work. Put the date on the face of the document, and note that materials will be re-priced if acceptance falls outside it.
Day rates and cost plus
There is a third option that suits genuinely open-ended work such as repairs and investigation: charge for time and materials at stated rates, with a cap or a review point the customer agrees to in advance. Be specific about what a day means (hours on site, travel included or not), what the materials mark-up is, and what happens when the cap is reached. Vagueness here is what turns a fair arrangement into an argument.
The one-line summary
A quotation transfers the risk of the job costing more to you, and buys certainty for the customer. An estimate keeps that risk with the customer, and buys flexibility for you. Neither is the right answer every time. Choosing without knowing which one you have chosen is always the wrong answer.
More guides
- How to price a building job so it still makes money
- What a quote must include to be safe in the UK
- How to work out your true hourly rate
- Exclusions and assumptions: the two lists that protect your price
- VAT for UK trades, and the domestic reverse charge
- CIS deductions explained, for subcontractors and contractors
- Payment terms, deposits and staged payments
- Variations and extras: how to get paid for work outside the quote
- Why quotes get rejected, and eight fixes that win more of them
- Domestic versus commercial: what changes in the way you quote
- Chasing late payment without losing the customer
Write the quote itself in a couple of minutes
BidReady turns the answers to a short set of questions into a professional quotation with the scope, the exclusions and the terms already in it. Write your first quote free, or see how it works.
This guide is general information for UK trades, written by the BidReady team. It is not legal, tax or financial advice. Rules change and individual circumstances differ, so take professional advice before acting on anything that matters.