Quote or estimate? The difference is legally significant

The short version

A quote is a fixed price. Once the customer accepts it, you have a contract at that figure and you cannot simply charge more because the job took longer than you thought. An estimate is your best guess, and the final bill can reasonably differ from it.

The label at the top of the page is not what decides it. If a document reads as a firm price for defined work, a court will treat it as a quote whatever you headed it.

When to quote

Quote when you can see the whole job. Supplying and fitting something to a known specification, a defined area, a fixed list of items. A fixed price is easier for the customer to say yes to, and it is worth more to you than an estimate because it removes their risk.

When to estimate

Estimate when something material is genuinely unknown: what is behind the wall, what condition the existing installation is in, how much of the substrate has to come out. Say plainly what the unknown is and what would change the figure, because an estimate with no stated variable reads to a customer exactly like a quote.

How far an estimate can move

There is no fixed percentage in law, but the working standard is that a final bill should not be materially more than the estimate without you having flagged it at the time. The safe practice is a clause that says you will stop and get written agreement before exceeding the estimate by more than an agreed margin, and then actually doing that.

Consumers have extra protection

Under the Consumer Rights Act 2015, work for a consumer must be done for a reasonable price where no price was fixed, and any price information you gave is binding to the extent the consumer relied on it. That makes vagueness expensive. Write the figure down, say what it covers, and say what it does not.