Contractor Invoice Calculator

Price contractor invoices from labor, materials, and job costs.

How is contractor invoice calculator worked out?

A contractor invoice total is labor (hours × rate) plus materials including any agreed markup, plus other job costs, plus tax — with retainage withheld and previous progress payments deducted to give the amount currently payable.

Contractor Invoice Calculator

Payable now

$6,660.00

Total amount claimed
$6,660.00
Retainage withheld
$0.00
Earned but not yet collectable.
Show the working
Labor$3,900.00
Materials at cost$2,400.00
Materials markup at 15%$360.00
Equipment & other job costs$0.00
Subtotal$6,660.00
Tax$0.00
Total claimed$6,660.00
Less retainage-$0.00
Less previous payments-$0.00
Payable now$6,660.00

Contractor invoices are checked against a contract before anyone releases money, so the maths has to be visible. Labor, materials and markup each follow different rules in most contracts, and retainage is withheld from the claim rather than deducted from your price — this calculator keeps all four separate so the number you claim is the number you can defend.

The formula

Labor = hours × hourly rate
Materials with markup = materials cost × (1 + markup %)
Subtotal = labor + materials with markup + other job costs
Tax = subtotal × tax rate
Amount claimed = subtotal + tax
Retainage = amount claimed × retainage %
Payable now = amount claimed − retainage − previous payments

Retainage is calculated on the full claim and withheld until the contract releases it, so it is not lost revenue — it is revenue you have earned and cannot yet collect. Tracking it separately on every claim makes the final release invoice a simple sum rather than a reconstruction.

Marking up materials without a dispute

Markup on materials is normal in construction, and it is normally in the contract. The problems start when it is applied at a rate nobody agreed, or hidden by quoting materials at a marked-up figure described as cost. Show the cost and the markup as separate lines at the rate your contract sets. A client who can see a 15% markup that they signed for rarely argues; a client who discovers one they cannot trace always does.

Retainage is a collection problem, not a pricing problem

Retainage is money you have earned and cannot yet collect, which makes it a cash-flow item rather than a discount. Show it on every claim so the withheld balance is always visible to both sides, and diarise the release date from your contract — retainage most often goes uncollected simply because nobody invoiced for it after practical completion.

Frequently asked questions

How do you calculate a contractor invoice?

Multiply labor hours by your labor rate, add materials at cost plus any contractually agreed markup, then add equipment and other job costs. Apply tax to that subtotal to get the amount claimed, then subtract any retainage withheld and any previous progress payments to get the amount payable now.

What is a typical markup on materials?

It varies widely by trade, region and contract, and there is no universal figure. What matters on the invoice is that the rate you apply is the rate your contract specifies, and that cost and markup appear as separate lines so the client can verify both.

How does retainage affect what I invoice?

Retainage does not reduce the value of your claim — you still invoice the full amount earned. It is withheld from what the client pays now and released later under the contract, usually at practical completion or after a defects period. Showing it separately keeps the earned amount and the collectable amount both visible.

Put the number on an invoice

The free invoice generator builds the document around your figures — line items, tax, payment terms — and downloads a print-ready PDF. No signup required.

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