Invoice vs. Estimate: What's the Difference?
By ActiveEngine · 4 min read · Last updated September 3, 2026
Definition of each
An estimate is a good-faith forecast of what a job will cost, sent before work begins. An invoice is a request for payment, sent after work is performed or a deposit is due.
An estimate says "here's what this should cost." An invoice says "here's what you owe." Both matter — they just do different jobs.
When to send which
Send an estimate when a client asks for pricing, before any work starts. Send an invoice when work is complete, a milestone is reached, or a contractually agreed deposit comes due.
The sequence that keeps everyone happy: estimate → client approves in writing → work happens → invoice. Never skip the written approval step.
See your exact numbers
Build a professional invoice PDF in under 60 seconds — free, no signup.
Try the free Field Invoice generator →Still pricing the job?
Build the quote or bid first with Field Estimate — then send it straight over as an invoice when the work is done.
Try Field Estimate free →Why sending the wrong one causes payment disputes
Label a forecast "invoice" and the client may pay it before work starts — then dispute the final bill when the numbers move. Label a final bill "estimate" and it lands in the "thinking about it" pile instead of accounts payable.
The label sets the expectation. Payment disputes often trace back to a document that said one thing and meant another.
Converting an estimate into an invoice
Carry the same line items, quantities, and rates across so the client can compare the two documents side by side. Show any variance as a clearly labeled change-order line, never a silently adjusted rate.
Field Estimate exports approved estimates straight into Field Invoice, so client details, line items, and the tax rate come across without retyping.