Quote, estimate or invoice: which one do you send?

These documents look alike: a header, a list of items, a total. What separates them is timing and commitment. A quote and an estimate come before the sale, a proforma sits in between, and an invoice comes after. Sending the wrong one can promise more than you meant to, or less than your client needs.

The short version

Estimate: a best guess

An estimate is an approximate price for work whose final scope you can’t pin down yet: a repair before you open the wall, a custom project that depends on choices the client hasn’t made. It tells the client what to budget for, and both sides understand the final bill may differ.

Say how the price could change and by roughly how much (“we’ll confirm before going more than 10% over”). That one sentence avoids most disputes.

Quote: a price you stand behind

A quote is a fixed offer for a defined set of products or services. If the client accepts it before it expires, that’s the price. That’s why quotes need a clear list of what’s included, a “valid until” date and short terms.

Quotes are the norm for products and well-defined services: wholesale orders, custom builds with a set specification, installations with a known scope. In many places an accepted quote can count as an agreement, so only quote what you’re ready to deliver at that price.

You’ll also see “quotation” (the same thing) and “proposal”, which usually means a quote plus a pitch: why you, how you’ll do it, timelines.

Proforma invoice: a preview

A proforma invoice is sent after the client agrees but before you invoice for real. It’s common in international trade, where a buyer needs it to arrange payment, import permits or financing, and when you ask for payment before shipping. It isn’t a demand for payment and usually doesn’t go in your accounting as a sale.

Invoice: a request for payment

An invoice records a completed sale and asks to be paid. It needs what your tax rules require, often an invoice number, tax details and a due date, and it goes in your books. If you quoted first, the invoice should match the accepted quote unless the client agreed to changes.

Which one should you send?

• You know exactly what the client is buying: send a quote.
• You can’t know the final scope until you start: send an estimate, and say how it might change.
• The client accepted and needs a document to pay or import: send a proforma.
• The goods shipped or the work is done: send an invoice.

Many sales go quote, then invoice. On Shopify that path can be quote, then draft order, then the order the client pays at checkout. See how to send quotes from Shopify.

This guide is general information, not legal or tax advice. Invoicing rules differ by country, so check what applies to you.