AI quoting and estimating.
What’s actually achievable.

On this page

1. 01 The short answer
2. 02 What AI genuinely does well on a quote
3. 03 Where it will quietly make a number up
4. 04 An honest test you can run in five minutes
5. 05 A setup that works: your numbers, its words
6. 06 When a built tool beats a chat window

The short answer

Split the quote into two jobs: the numbers and the words. AI is excellent at the words — clear scope, what’s included, what isn’t, terms, a professional tone, done in a minute. It is unreliable at the numbers, for one simple reason: it doesn’t know yours, and when it doesn’t know something it makes a plausible guess instead of stopping.

So the rule is: your numbers, its words. Give it the rates and the quantities, let it write the document, check every figure before it goes. A quote is a commitment — if the customer accepts it, that’s the price — and a number you didn’t check is a number you’ve agreed to without knowing.

What AI genuinely does well on a quote

• Turning site notes into a scope. “Strip 60m² slate, new membrane, 2 valleys, re-bed ridge, scaffold front only” becomes a clear paragraph a customer understands.
• The exclusions. It’s good at the list of what’s not included — the bit that saves you an argument in week three — if you tell it the type of job.
• Options. “Write this as a good / better / best quote with the three roof-covering options I’ve given you.” Ten minutes of formatting, done.
• Consistency. Every quote reads like it came from the same firm, in the same voice, with the same terms.
• The follow-up. The chaser email a week later, polite and short.
• Checking your own quote. “What have I missed on a job like this?” It will suggest the skip, the scaffold licence, the waste transfer note. You decide which apply.

Where it will quietly make a number up

The common thread: a general AI model is built to produce a complete, plausible answer. On a quote you want the opposite — a tool that stops and says “I don’t have that figure”. That’s why the numbers belong somewhere else.

An honest test you can run in five minutes

Don’t take my word for it. Open whichever AI tool you use and try this:

1. 01

   Pick a job you quoted last month, where you know the real figure.

2. 02

   Describe it the way a customer would — “re-slate the front of a 1930s semi in Truro” — and ask for a price.

3. 03

   Compare it to your real quote. Then ask the same question again in a new chat, and see if you get the same number.

You won’t. You’ll get two different confident figures, both some distance from yours. That is the tool working exactly as designed, and it’s all you need to know about letting it price anything.

A setup that works: your numbers, its words

1. 01

   Keep a rates sheet. Labour per day by role, your standard material prices from the merchant, your markup, your standard extras. One page, updated when prices move.

2. 02

   Measure on site, write the quantities down. They never come from the AI.

3. 03

   Do the sums somewhere that can’t improvise — a spreadsheet or a calculator built for your firm. Rates times quantities, your markup, VAT. Fixed, repeatable, boring.

4. 04

   Give AI the scope, the totals and your terms, and ask for the document. No customer name or address — those go in afterwards, by hand.

5. 05

   Read it like the customer will. Every figure against your sheet, every exclusion, the start date. Then send.

When a built tool beats a chat window

If you quote the same shape of job again and again, the spreadsheet step is worth replacing with something built for the purpose: a calculator on your phone or your website that asks the six questions that drive the price — bedrooms, square metres, number of circuits, access — applies your rates, and produces the quote. The customer can even run it themselves on your site and arrive with a ballpark already in their head.

The difference from AI is the one that matters: a built calculator does the same sum the same way every time, from figures you set, and it never invents one. It’s the kind of tool I build for Cornish trades, fixed price, and I’ll say honestly when a spreadsheet would do.

Where this comes from

• ICO — Artificial intelligence and data protection guidance ↗
• Citizens Advice — If a trader quotes you a price: what a quote commits a business to ↗

This is plain-English guidance for small businesses, not formal legal advice. Where something genuinely needs a solicitor or a data-protection specialist, I'll tell you straight.

Straight answers

Can AI price a job for me?

Not on its own, and not safely. A general AI tool doesn’t know your rates, your margins, your suppliers’ prices this month or what the site is like. Ask it to price a job and it will give you a confident number that is somewhere in the national average — which is to say, wrong for Cornwall, wrong for you, and wrong for that site. What it can do well is the arithmetic and the writing, once you’ve given it the numbers.

What’s the difference between AI quoting and a quoting tool?

A quoting tool — a spreadsheet, a calculator built for your firm, estimating software — does the sums with your figures, the same way every time. AI drafts text and reasons loosely; it can also do sums, but it will sometimes do them wrong without telling you. The right setup is your numbers in a tool that calculates reliably, with AI used for the words around them.

Will it make up a price?

Yes, if you let it. That’s the single most important thing to understand about these tools. Asked for a number it doesn’t have, a general AI model produces a plausible one rather than saying it doesn’t know. On a quote, a plausible wrong number is worse than no number.

Can I give it my price list?

Yes, and that’s the useful version. Paste your rates — labour per day, standard material prices, your markup — and ask it to build the quote from those. Check every line. It will be right most of the time, and the time it isn’t will be the one that costs you.

Is it worth building a proper quoting tool?

If you quote the same kind of job repeatedly — EICRs by number of circuits, re-roofs by square metre, treatment plants by bedrooms — yes. A calculator built around your own rates turns a forty-minute quote into a five-minute one and never invents a figure. If every job is different, a good template and AI for the writing is probably enough.

What about the customer’s details?

Same rule as everything else: the job goes in, the person doesn’t. Scope, measurements, materials, your rates — fine. Name, address, phone number — add them afterwards, by hand.

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