Estimate vs invoice: what is the difference?

They look similar, but an estimate and an invoice do two very different jobs. Getting them right keeps you out of arguments and gets you paid.

The short version

An estimate (also called a quote or a bid) is what you send before the work to say what it will cost. An invoice is what you send after the work to ask for payment. Same layout, different purpose, different timing.

What an estimate is for

An estimate sets expectations before anyone commits. It lists the work, the price, and any assumptions, so the customer knows what they are agreeing to. A good estimate wins the job and protects you if the scope changes later. It is not a demand for payment, it is an offer.

Estimates are usually not legally binding on their own, but a signed or accepted estimate is strong evidence of what was agreed. Note whether your price is fixed or an approximate range, and how long it is good for.

What an invoice is for

An invoice is a request for payment for work you have done or goods you delivered. It should have an invoice number, a date, a due date, the itemized work and the total owed. Unlike an estimate, an invoice is an accounts-receivable document, it is the thing you track, chase and record as income.

How they work together

On most jobs the flow is simple: send an estimate, get it approved, do the work, then turn that estimate into an invoice. If nothing changed, the numbers match. If the scope grew, your invoice reflects the extras (ideally after you flagged them with a change order or a quick text so there are no surprises).

Good software lets you build the estimate once and convert it to an invoice in a tap, so you are not retyping anything.