Quote vs estimate vs tender: what’s the legal difference?

The words "quote" and "estimate" are used interchangeably in conversation, which is a problem, because in building work they mean different things and carry different commitments. Agreeing to what you think is a fixed price, when the document is actually an estimate, is one of the most common ways a budget quietly slips. The third term, "tender", matters on bigger jobs. Knowing which one you are holding is the first step to knowing what you have actually agreed to.

This guide sets out the difference and how to make sure you are getting a fixed price. For reading the document itself once you have it, see how to read a builder’s quote.

A quote: a fixed price#

A quote (or quotation) is a fixed price the builder commits to for the work described. Once you accept it, that is the price, barring genuine variations you agree to along the way. A quote is the document you want for any well-defined job, because it puts the risk of the work costing more than expected on the builder, not on you.

For a quote to hold, it has to describe the scope in enough detail to pin the builder to it. "Fixed price: £20,000" with no detail is a number without a job attached. A real quote says what the £20,000 buys.

An estimate: an informed guess#

An estimate is the builder’s best guess at the likely cost, and it can change as the work progresses. It is useful early on, when the scope is not yet settled and you want a rough sense of the budget. The risk is treating an estimate as though it were a fixed price: the final bill can legitimately differ, and you have less ground to object if it climbs.

An estimate should still be given in good faith and be reasonably accurate. A final cost wildly above an estimate, with no agreed variations to explain it, can be challenged. But the safe move is to convert an estimate you are relying on into a written quote before work begins.

A tender: a formal competitive bid#

A tender is a formal process, used on larger or more complex projects, where you (often through an architect or surveyor) issue a detailed specification and invite builders to submit priced bids for exactly that scope. Because every builder prices the same specification, tenders produce the most directly comparable bids you can get. The trade-off is the upfront effort of producing a full specification, which is why tenders suit bigger jobs rather than a single room.

Why the distinction protects your money#

The label changes your legal position. A quote you accept forms a binding agreement on price. An estimate sets an expectation that can move. If you do not know which you are holding, you do not know whether the number is a commitment or a guess. On a large job, that difference can be thousands of pounds.

How to make sure you have a fixed price#

1. Check the document is labelled "quotation" or "fixed price", not "estimate".
2. Make sure it describes the scope in enough detail to hold the builder to it.
3. Confirm in writing that the figure is fixed, barring agreed variations.
4. Agree how variations will be handled: in writing, priced, and approved before the extra work is done.

A fixed-price quote can still change through genuine variations, where you alter the scope or hidden problems are uncovered, but it cannot rise simply because the job took the builder longer than they hoped. For how to handle those changes fairly, and the deposit and payment structure to expect, see how to tell if a quote is too high.

Once you have a proper fixed-price quote, the remaining question is whether the price is fair. Paste or upload it into Check the Quote and we check every line against current UK market rates for your postcode and flag anything above the fair range. Your first check is free.