Quote or Estimate? The Difference, and Which to Send for Heating Jobs

Ever priced up a job and stopped to wonder what you should actually be sending the customer, a quote or an estimate? Plenty of heating & plumbing businesses use the two words as if they mean the same thing. They don’t, and the difference between a quote and an estimate is what decides whether you’re stuck with your price when the job turns out bigger than it looked from first visit.

This guide covers which one to send when, what belongs on both, how long a quote should stay valid, and what to do when the work grows halfway through.

The difference between a quote and an estimate

A quote is a fixed price for a defined piece of work. Once the customer accepts it, that’s the price, and you’re both tied to it.

An estimate is your best assessment of what the job will cost based on what you know when you price it. It’s a considered figure rather than a guess, but it isn’t fixed. If something unforeseen needs replacing, and an estimate gives you room to move. A quote doesn’t.

 Most customers prefer a quote because it gives them some certainty on how much a job will cost. But it isn’t always viable.

The test is how much of the job you can actually see. If you can see all of it, quote. If you’re pricing around something you can’t see yet, estimate.

When to send a quote

Quote when you can see the whole job and you’ve priced work like it before:

• Like-for-like boiler swaps where the pipework and flue run are already in place
• Annual services and safety checks
• Landlord certificates and repeat compliance work
• Small repairs where you know the part and the time
• Anything you’ve done fifty times and could price from the van

A fixed price is easier for the customer to say yes to, and it’s easier for you to invoice. If you can quote, quote.

When to send an estimate

Estimate when part of the job is still hidden:

• System upgrades where you can’t see the existing pipework
• Older properties where nothing is where it should be
• Anything behind a wall, under a floor, or above a ceiling
• Heat pump work that needs a proper survey and heat loss calculation before the price means anything
• Jobs where the customer is still deciding on the scope

An estimate is also the honest answer when someone wants a number over the phone. You can give them a range to work with without committing to a price for a system you haven’t seen.

Gas Engineer Software treats these as separate documents, so you pick Estimate, Quote or Invoice when you create the record rather than sending a quote and hoping the customer reads the small print.

Creating estimates and quotes in Gas Engineer Software

Estimate, Quote and Invoice are separate forms in GES, so you choose which one you’re issuing at the point you create it.

From there, you can create a draft with AI or:

• Build the price up from your saved line item templates
• Set your default terms & validity period once in settings for it to be included on every quote/estimate
• Keep track of what’s outstanding with quote statuses
• Convert to an invoice once the work is agreed

Is a quote legally binding?

Once the customer accepts your quote, you have a contract at that price, and it works both ways. They can’t knock money off because they’ve had second thoughts. You can’t add to it because your merchant put copper up the week you fitted it.

That second half is where heating businesses tend to lose money. Let’s say you quoted a full system one week, then the customer sat on it for six weeks. By the time you’re ordering, your material costs might have risen. Without a validity period and a price-change clause on the quote, that gap comes out of your margin.

Is a quote a contract?

Not by itself. A quote is an offer. It becomes a contract the moment the customer accepts it, which is why you want that acceptance in writing rather than a nod on the driveway. A text saying “yes, go ahead with that” is worth having when someone later claims they agreed to something different.

Is an estimate legally binding?

An estimate isn’t a fixed price, so you aren’t held to the exact figure. It isn’t a free pass either. You’re expected to have given it honestly, based on what you knew, and to charge a reasonable amount for the work you actually did.

Where no price has been agreed at all, the customer is expected to pay a reasonable price for the job. “Reasonable” is exactly the sort of thing that ends up being argued about after the fact, which is the reason to put a figure and your assumptions in writing even when you’re only estimating.

What belongs on a quote and an estimate

Since both contain the scope of work, they can look quite similar. The difference is in the terms.

Be sure to include enough detail that nobody can argue about what was included, the price broken into line items where it helps, and the assumptions you’ve priced against.

The part most engineers skip is the exclusions, and it’s the part that costs money. Spell out what isn’t in the price.

Line item templates help here. Build the wording once for the jobs you price regularly, and the exclusions go out with every quote instead of the ones you remember.

How long is a quote valid for?

This is up to you. Thirty days is the usual window in the trade, and it’s a sensible default. It’s long enough for a customer to think about a boiler and short enough that your material prices won’t move much.

Always put the validity window on the quote itself. Something as plain as “This quote is valid for 30 days from the date of issue. After that, we may need to re-price to reflect current material costs” does the job. If you’re pricing something with a long lead time or volatile parts, shorten it and say why.

You don’t want to be typing that line every time. In Gas Engineer Software you can save default quote notes in your settings, and they pull through onto every new quote automatically. Set it once and save time on each quote.

Read our full guide on pricing a heating & plumbing job.

Can you change a quote after it’s been accepted?

Not without informing your customer. Once a quote is accepted, the price stands unless you agree a change with the customer. This is crucial if you notice that the scope of work is different to what was laid out in the quote, but also why many heating & plumbing businesses are opting for estimates rather than quotes.

In our guide to what to do when a customer refuses to pay, you’ll see that most cases are when paperwork doesn’t match the work done on-site, and therefore protect your business.

What if the customer only wants part of the job?

This is common on multi-item quotes, where you’ve priced several jobs at one address and the customer only wants to go forward with some of them.

Typically it’s best to re-issue rather than crossing lines out as you may have offered a better deal for all the different parts.

Creating your quote digitally means this is an easy edit and re-issue.

Common questions

Does a quote have to be in writing?

Legally, no, but a verbal price is impossible to prove and impossible to defend, and it’s the first thing that unravels when a customer disputes the bill.

Can a customer refuse to pay more than the estimate?

They can certainly argue about it, and the more your final bill exceeds your estimate, the better their argument gets. If the price is heading well past what you estimated, tell them before you do the work rather than at the invoice stage.

What if I’ve made a mistake in my quote?

Tell the customer as soon as you spot it and before they accept, and you can withdraw or correct it. Once they’ve accepted, you’re in the realm of asking nicely rather than insisting, so it’s worth a second look at your figures before you send anything out.

Should I be chasing quotes I’ve sent?

Yes, and most engineers don’t. Quotes go quiet because customers get busy, not because they’ve said no. Quote statuses in GES show you which are won, lost and still waiting, so the ones sitting in limbo are visible instead of forgotten. Our blog on why your quotes aren’t turning into jobs covers the follow-up side.