Invoice vs estimate
A factual comparison of an invoice and an estimate: their purpose, timing and place in a small-business workflow.
What is an invoice?
An invoice records an amount now owed for supplied work, products or an agreed stage.
What is an estimate?
An estimate is a reasoned prediction of likely cost where the final scope, quantities or time may change.
Key differences
| Point | an invoice | an estimate |
|---|---|---|
| Amount | Actual amount billed | Expected amount |
| Timing | At a billing point | Before uncertain work |
| Customer action | Pay or query | Assess and approve proceeding |
When should you use an invoice?
Use it when you are entitled to bill under the agreement and can state the actual amount due.
When should you use an estimate?
Use it before work when uncertainty makes a firm price impractical, and state the assumptions clearly.
Example
A repairer estimates 6 to 9 hours after an initial inspection. The final invoice records 7.5 hours plus the parts actually used.
Can one replace the other?
No. An estimate prepares the customer for likely cost; it is not a request to pay. The final invoice should reflect the agreed charging basis and actual billable result.