What actually separates the two
A quote is meant to be a fixed price. State consumer affairs guidance is consistent on this: it should list the work, parts and labour it covers, and give a time limit for how long it stays valid. Once a job is offered at a stated price and the client accepts it, including its conditions, that acceptance turns the quote into a binding contract at that number. Neither side can walk away from it or change it without the other's agreement, doing so is a breach of that contract in its own right. Consumer Affairs Victoria's own guidance for tradespeople adds a few specifics worth spelling out on any quote before the client signs off: whether it covers transport to and from the job, call-out fees, weekend or public holiday rates, and how a mid-job change to the price or timeframe gets handled. A quote doesn't strictly have to be in writing to bind both sides, but every state regulator's advice lands the same place: document it, since a documented quote is what actually protects a trade if a dispute shows up later.
An estimate is the opposite. It's an educated guess at the cost, given before the full extent of the job or the exact materials needed are actually known, and it's allowed to be verbal. It's also allowed to move as the job reveals more, though regulators are clear the final figure "should not be too much more" than what was estimated.
What each one actually commits you to
Which one gets written on the job decides what happens if it runs over budget.
| Aspect | Quote | Estimate |
|---|---|---|
| Form | Usually written and itemised, with a time limit | Can be given verbally |
| The price, once given | Fixed. Binding on both sides once accepted | Approximate. Can move as the job reveals more |
| Extra cost mid-job | Needs the client's agreement to a written variation before it can be charged | Can be adjusted, but shouldn't land far past the figure given |
| Charging to prepare it | A quote fee is legitimate if the job needs inspecting or partly pulling apart first, usually credited back if the job goes ahead | Not typically charged for |
What this means for a job that runs over
Take our job quote calculator's own worked example: $800 in materials at a 15% markup ($920) plus 8 hours' labour at $85 an hour ($680) comes to a $1,600 subtotal, $1,760 once GST is added. Now say the job turns up a real surprise, rotted subfloor under the job that needs another $300 in materials and 2 extra hours on site. That's another $345 in marked-up materials and $170 in labour, pushing the subtotal to $2,115 and the GST-inclusive total to $2,326.50, a $566.50 jump, about 32% higher than the original figure.
If that original number was sent as a quote, that extra $566.50 can't just be added to the final invoice. It needs the client's agreement to a written variation before the extra work is even done, otherwise the job stays capped at the original $1,760 and the difference comes out of the trade's own margin. If it was sent as an estimate, the total is allowed to move to reflect the real cost, but a jump this size is exactly the kind of gap regulators say should be flagged and discussed with the client before it shows up on the final bill unannounced. Either way, the safer habit once a surprise like this turns up is the same one state consumer affairs offices recommend: put the real number in writing and get it agreed before the extra work goes ahead, rather than letting a verbal estimate carry all the way through to an invoice the client hasn't seen coming.
Common questions
What's the legal difference between a quote and an estimate in Australia?
A quote is a fixed price that becomes a binding contract once a client accepts it, and neither side can change it without the other's agreement. An estimate is an approximate figure given before the full scope of the job is known, it can move, but consumer affairs guidance says the final cost shouldn't land far past what was estimated.
Can a tradie charge more than they quoted if a job costs more than expected?
Not without the client's agreement. A quote is a fixed price once accepted, so any extra cost needs the client's written agreement to a variation before the extra work is done. Charging more without that agreement is a breach of the contract the quote itself created.
Can a tradie charge a client just to prepare a quote?
Yes, it's a recognised practice, particularly when a job needs to be inspected, tested or partly pulled apart to work out a price. The quote fee is usually credited back off the final bill if the client goes ahead with the job.
Is locking in a price the same legal idea as getting GST right?
Different law, same discipline. Our GST subtraction guide covers the same 'use the defined method, not the number that feels right' habit applied to tax law instead of consumer law: the word written on a job decides whether its price is locked in, the same way the correct formula decides whether a GST figure is right.
Sources
Quote vs estimate definitions, binding-contract rules and the "not too much more" standard for estimates, quoted directly: Consumer Protection WA, Ask us: Estimates and quotes. Written-quote content, time limits, the legitimacy of a quote fee and its usual crediting against the final bill, quoted directly: NT Consumer Affairs, Quotes and Estimates fact sheet (2 Jan 2024). What a quote should clarify (transport, call-out fees, weekend/public holiday rates, handling mid-job changes) and that a quote can be verbal as long as it's clear, quoted directly: Consumer Affairs Victoria, Giving quotes: tradespeople and small works. Worked $1,760 job figure: this site's own job quote calculator. All fetched July 2026.