Estimates and invoices trip up a lot of new contractors because they look almost identical — same header, same line items, same total. The difference is timing and purpose: an estimate is a promise about the future, and an invoice is a bill for the past. Send the wrong one at the wrong time and you either look unprofessional or you don't get paid.
The estimate: before the work
An estimate (sometimes called a quote or bid) goes out before the job starts. Its purpose is to win the work and set expectations. It's a good-faith projection of what the job will cost, itemized so the customer sees the value and you're protected if the scope changes. Key traits:
- Sent before work begins, during the sales stage.
- Includes an expiration ("valid 30 days") and terms about what could change the price.
- Often asks for a deposit to schedule the job.
- Its job is to get a yes.
The invoice: after the work
An invoice goes out after the work is done (or at agreed milestones). Its purpose is to get you paid. It's a formal request for payment with a due date and payment instructions. Key traits:
- Sent after the work, or at milestones for bigger jobs.
- Has an invoice number and a due date ("Net 15," "due on receipt").
- Shows payment methods and any deposit already paid, with the balance owed.
- Its job is to get you paid.
Side by side
| Estimate | Invoice | |
|---|---|---|
| When | Before the work | After the work / at milestones |
| Purpose | Win the job | Get paid |
| Amount | Projected | Final amount due |
| Key extras | Expiration, deposit request | Due date, payment methods |
| Binding? | Good-faith projection | A bill owed |
How one becomes the other
The clean workflow is: send an estimate → customer accepts → do the work → convert the same line items into an invoice, adjust for any approved changes, add a due date, and send it. You shouldn't be re-typing the job twice. QuoteAnyJob's free tools share the same line-item structure across both documents, so the details carry straight from your estimate into your invoice — no double entry, no missed items.
New to writing either one? Start with how to write an estimate that wins jobs, then build your first one in the estimate templates.