Quote vs Estimate vs Invoice: Differences Explained

Quotes, estimates and invoices are all documents about price, and they can look almost identical. What separates them is when you send them and how firm the number is. An estimate is an approximate price before the work. A quote is a fixed price before the work. An invoice is the bill after the work.

Using the right one protects you. Send an "estimate" when you meant a firm quote and a client may reasonably argue that a higher final bill is fine. Send a "quote" when you only meant a rough guess and you may be held to a price you cannot deliver.

The difference in one table

	Estimate	Quote	Invoice
When	Before the work	Before the work	After the work (or a stage of it)
Purpose	Give a rough idea of cost	Offer a fixed price	Request payment
How firm	Approximate; can change	Fixed if accepted, for the stated scope	Final amount owed
Binding?	Generally not	Usually, once accepted	Records a debt
Validity	Indicative	Valid until a stated date	Due by a stated date
Key wording	"Estimate", "approximately"	"Quotation", "valid until"	"Invoice", "amount due", "due by"

What is an estimate?

An estimate is your best guess at what a job will cost, based on what you know now. It is useful when the scope is not yet clear - a repair where you cannot see the damage until you open the wall, or a project where the client has not decided on the details. A good estimate says it is an estimate, explains what it is based on and gives a range or a margin ("likely £2,000 to £2,500, depending on the condition of the joists").

What is a quote?

A quote (or quotation) is a fixed price for a defined piece of work. If the client accepts it, you are generally expected to do that work for that price. That makes the scope the most important part: list exactly what is included, what is not, any assumptions, and how long the price is valid - costs change, and a quote from six months ago should not still bind you. Changes the client asks for later should be quoted separately.

You can create one with the free quotation generator, which uses the same designs as the invoice generator so the two documents match.

What is an invoice?

An invoice is sent after the goods or services have been delivered (or after an agreed stage) and asks for payment. It should match the accepted quote line for line, so the client can approve it quickly. If the final amount differs from the quote, explain why on the invoice - agreed extras, changed quantities - rather than leaving the client to spot the difference. See how to write an invoice for a full walkthrough.

How they fit together

1. Estimate (optional) - the client wants a ballpark figure before deciding.
2. Quote - you define the scope and fix the price. The client accepts.
3. Work is done. For long jobs, you may invoice a deposit or stages along the way.
4. Invoice - you bill for the work, referencing the quote.
5. Receipt - issued once payment is received, if needed.

Turning a quote into an invoice

The simplest way to keep the invoice consistent with the quote is to build it from the quote. Use the same line descriptions, quantities and prices, then change the title to "Invoice", add an invoice number, the invoice date, a due date and your payment details. Clients compare the two line by line, and any wording that changed looks like a price rise even when it is not. On this site, a quote made in the quotation generator can be carried into the invoice generator so you do not retype anything.

Which should you send?

• The scope is clear and you can price it: send a quote.
• The scope is unclear, or costs depend on things you cannot know yet: send an estimate, and follow it with a quote once you know more.
• The work is done: send an invoice.

Frequently asked questions

Is a quote legally binding?

Once a client accepts a quote, it generally forms part of the contract, so you are expected to honour the price for the work described. An estimate is generally not treated as a fixed price, though a final bill that is far above an estimate can still be disputed. Contract law varies by country, so get advice for large or unusual jobs.

Can an invoice be higher than the quote?

Only for work outside the quoted scope that the client agreed to. Document variations in writing as they happen and list them separately on the invoice.

How long should a quote be valid?

Thirty days is common. Use a shorter period when material prices are volatile, and always print the expiry date on the quote.