If you've ever had a client surprised by the final price, or had a project scope creep out of control without any written agreement, you probably sent an invoice when you should have started with an estimate. Here's everything you need to know.
What Is an Estimate?
An estimate (sometimes called a quote or proposal) is a document you send to a client before work begins. It outlines the expected scope of work and the projected cost. Critically, it is not a payment demand — it's an offer for approval.
Estimates communicate:
- What work you plan to do
- How much it will likely cost
- Any assumptions or conditions (e.g., "price assumes two revision rounds")
An estimate may or may not be legally binding depending on your jurisdiction and how it's worded, but even a non-binding estimate sets clear expectations — which is the whole point.
Key word: "Estimate" — it implies the final price may vary slightly based on actual work. If you want a firm, fixed price that won't change, use "Quote" instead. Invo supports both terms.
What Is an Invoice?
An invoice is a formal payment request sent after work is completed (or at a billing milestone). Unlike an estimate, an invoice represents a specific, final amount owed. It is a legal document and forms part of your financial records.
Invoices communicate:
- Exactly what was delivered
- The exact amount due
- The due date for payment
- Payment instructions
Once sent, a client is legally obligated to pay the invoice amount within the stated terms (assuming the work was completed as agreed).
Key Differences at a Glance
When to Use an Estimate
Send an estimate when:
- Starting a new project — always get written agreement on scope and price before you start working
- Working with a new client — it establishes expectations and professionalism from day one
- The scope might evolve — an estimate gives you flexibility to adjust the final invoice if work grows
- The client needs budget approval — many businesses require an estimate to get internal sign-off
- You're bidding against others — a polished estimate makes you look serious and competitive
When to Use an Invoice
Send an invoice when:
- Work is complete — this is the most common scenario
- A billing milestone is reached — e.g., 50% upfront, 50% on delivery
- A monthly retainer is due — regular clients on retainer receive invoices on a recurring schedule
- A deposit is required before starting — use a partial invoice for the deposit amount
The Ideal Workflow: Estimate → Invoice
The best practice for most freelancers and small businesses is a two-step process:
Before any work begins, create and send an estimate outlining scope and expected cost. Wait for written approval (even just an email reply saying "approved" is sufficient).
Complete the project with the agreed scope in mind. If the scope changes significantly, discuss it with the client before it impacts the final price — no one likes surprise invoices.
In Invo, open the approved estimate and tap Convert to Invoice. All line items, client details, and amounts carry over automatically. Adjust any items if the scope changed (with the client's knowledge), set the due date, and send.
Monitor the invoice status from your Ledger Desk. When payment arrives, mark it as Paid and move on to the next project.
Pro tip: Converting an estimate to an invoice in Invo takes one tap. No re-entering data, no reformatting — the invoice is ready to send in seconds.
Common Questions
Can I skip the estimate and go straight to an invoice?
Yes — for simple, recurring, or fixed-price work with established clients, it's fine to skip straight to the invoice. Use estimates primarily for new projects, new clients, or complex scopes.
What if my estimate was $1,000 but the work ended up being $1,300?
Talk to the client before sending the invoice. Explain why the scope grew and get verbal or written approval for the higher amount. Never send an invoice significantly higher than the estimate without a conversation first — it damages trust and often leads to disputes.
Do estimates expire?
They should. Best practice is to include an expiry date (e.g., "This estimate is valid for 30 days"). This protects you from a client coming back six months later expecting the same price.
Create estimates, get approval, and convert to invoices in one tap — right from your iPhone.
Summary
An estimate comes first, an invoice comes last. The estimate gets you agreement; the invoice gets you paid. Used together, they create a clear paper trail, set professional expectations, and eliminate the most common sources of client conflict. And with Invo converting between the two takes a single tap — so there's no reason not to use both.