Construction Lien Calculator
Lien amount and filing deadline from project payments.
About this calculator
A mechanic's lien lets a contractor, subcontractor, or material supplier claim a security interest against a property when they've performed work but haven't been paid in full. This calculator starts by adding the original contract amount to any change orders to get the total amount earned, then subtracts payments already received to find the unpaid balance — the principal of the lien. Because unpaid construction debts frequently accrue statutory interest, the calculator applies simple daily interest (annual rate divided by 365, times days since the last payment) to that unpaid balance, then adds flat filing and attorney fees to produce the total lien amount you could claim. Separately, it tracks a hard filing deadline: most states give contractors a fixed window — commonly 60 to 120 days — from the date of last work performed to actually record the lien, or the right to lien is lost entirely regardless of how much is owed.
The calculator subtracts days already elapsed since your last work from your state's deadline to show days remaining, flagging the situation as critical once 14 days or fewer are left. It also gives a rough estimate of enforcement cost — what it might take in additional legal fees to actually foreclose on the lien if the debt isn't voluntarily paid — set here as a simple multiple of the initial attorney fee, useful for weighing whether pursuing the lien is financially worthwhile against a small balance. Lien deadlines and interest rates are state-specific and strictly enforced, so verify your jurisdiction's actual rules well before the calculated deadline arrives.
Legal Disclaimer
This calculator provides general estimates only and does not constitute legal advice. Laws, regulations, and court procedures vary significantly by jurisdiction. Consult a licensed attorney in your area for advice specific to your situation.
How to Use This Calculator
- Enter Original Contract Amount and Change Orders to establish total earned amount.
- Input Payments Already Received and Retainage Held % to calculate unpaid balance.
- Set Statutory Interest Rate and Days Since Last Payment for accrued interest.
- Enter Filing Fee and Attorney Fee to prepare and file the mechanic's lien.
- Check State Filing Deadline vs. Days Since Last Work — you must file before the deadline or lose lien rights.
- Review Total Lien Amount to determine if filing is financially worthwhile given collection costs.
How the result changes with Original Contract Amount ($)
| Original Contract Amount ($) | Total Lien Amount | Unpaid Balance |
|---|---|---|
| 42,500 | $6,260.96 | $4,500.00 |
| 63,750 | $28,034.93 | $25,750.00 |
| 127,500 | $93,356.85 | $89,500.00 |
| 212,500 | $180,452.74 | $174,500.00 |
What each input means
- Original Contract Amount ($)
- Original contract or invoice amount for work performed.
- Change Orders / Extras ($)
- Additional work authorized via change orders.
- Payments Already Received ($)
- Total payments received to date.
- Retainage Held (%)
- Percentage of contract held as retainage.
- Statutory Interest Rate (%)
- Annual interest rate on unpaid amounts (varies by state, often 10-12%).
- Days Since Last Payment
- Calendar days since the last payment was received.
- Lien Filing Fee ($)
- County fee to record the mechanic's lien.
- Attorney Fee ($)
- Attorney fee to prepare and file the lien.
- State Filing Deadline (days)
- Days after last work to file a lien (varies by state: 60-120 typical).
- Days Since Last Work
- Calendar days since you last performed work on the project.
What each result means
- Total Lien Amount
- Unpaid balance + interest + filing and attorney fees.
- Unpaid Balance
- Total earned minus payments received.
- Total Earned (Contract + Changes)
- Original contract plus change orders.
- Payments Received
- Total payments received to date.
- Retainage Held
- Amount withheld as retainage.
- Accrued Interest
- Simple interest on unpaid balance.
- Days Until Filing Deadline
- Days remaining before the lien filing deadline expires.
- Urgency Level (1-3)
- 1 = comfortable, 2 = file soon, 3 = critical (14 days or less).
- Lien as % of Contract
- Total lien amount as a percentage of total earned.
- Estimated Enforcement Cost
- Rough estimate of litigation costs to foreclose on the lien.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersOriginal Contract Amount ($) = 85000, Change Orders / Extras ($) = 12000, Payments Already Received ($) = 50000, Retainage Held (%) = 10 = 10 input(s) provided
- Calculate Total Lien AmountTotal Lien Amount = r(totalLienAmount)49808.9 = $49,808.9
- Calculate Unpaid BalanceUnpaid Balance = r(unpaidBalance)47000 = $47,000
- Calculate Total EarnedTotal Earned = r(totalEarned)97000 = $97,000
- Calculate Payments ReceivedPayments Received = 5000050000 = $50,000
Engine last updated . Checked against 3 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
What's the difference between the unpaid balance and the total lien amount?
Unpaid balance is just the principal you're owed — the original contract amount plus change orders, minus payments already received. The total lien amount is what you could actually claim in the lien filing: that same unpaid balance plus accrued statutory interest (calculated daily on the unpaid balance since your last payment) plus the flat filing fee and attorney fee needed to record and prepare it.
How is the filing deadline urgency calculated?
The calculator subtracts your Days Since Last Work from your state's Days to File Lien deadline to get days remaining, then flags urgency as critical (level 3) at 14 days or fewer remaining, soon (level 2) at 30 days or fewer, and comfortable (level 1) otherwise. This deadline is separate from days since your last payment — it runs from the date you last performed physical work on the project, and once it expires the right to file a lien is typically lost entirely regardless of how much is owed.
How is the accrued interest on the unpaid balance calculated?
It uses simple daily interest: your annual Statutory Interest Rate is divided by 365 to get a daily rate, which is then multiplied by the unpaid balance and by the number of days since your last payment. This is simple interest, not compounding, so it accrues linearly and doesn't add interest on top of previously accrued interest.
Is the Estimated Enforcement Cost a reliable prediction of what litigation will actually cost?
No — it's a deliberately rough placeholder, calculated in this calculator as simply five times your entered Attorney Fee input. It's meant only as a directional gut-check for weighing whether pursuing a lien on a small balance is financially worthwhile against likely legal costs, not an estimate grounded in actual case complexity, hourly rates, or how far a dispute might proceed toward foreclosure.
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