Invoice vs. Estimate: What's the Difference?
When to send a quote and when to send a bill — and how estimates, proforma invoices, and receipts fit in.
New freelancers and business owners often mix these up. The difference is timing and purpose: an estimate comes before the work and says what it will probably cost; an invoice comes after (or as agreed) and says what is owed.
Estimate: the quote
An estimate (or quote) is your proposal. It lists the work you plan to do and the expected price, but it doesn't request payment — it requests approval. Estimates are usually non-binding unless you state otherwise, so label them clearly.
Invoice: the bill
An invoice is a formal demand for payment for work done or goods delivered. It has a unique number, an invoice date, payment terms, and a due date. Once an estimate is approved and the work is complete, the invoice is the document that gets you paid.
Where the other documents fit
- Proforma invoice: a preview of the final invoice, often used for advance payments or international shipments.
- Receipt: proof that payment was received — sent after the money arrives, not before.
- Credit note: documents a refund or a reduction in what the client owes.
- Purchase order: the client's formal order to you, which your invoice may reference.