Construction-to-Permanent Calculator
This construction-to-permanent calculator models both phases: interest-only during the build, then the mortgage payment after conversion.
By Onias Derilus, Mortgage Capital · NMLS# 1859012 · Last Updated: June 2026
One closing covers both phases, so you pay closing costs once. The permanent rate may be locked up front with an extended lock or float until completion. Estimate only.
A construction-to-permanent loan closes once and covers both phases: interest-only draws while the home is built, then conversion to a standard amortizing mortgage at completion.
The single closing is the main advantage. A separate construction loan followed by a refinance means two sets of closing costs and a second underwriting at whatever rates exist when the build ends.
These figures are estimates. For neutral, official guidance on mortgage costs and what lenders can charge, see the CFPB's Owning a Home guide.
How to Use This Calculator
- 1
Enter total project cost including land, hard costs, soft costs and contingency.
- 2
Enter your down payment or land equity.
- 3
Enter the construction rate and expected build time.
- 4
Enter the permanent rate and term, plus taxes and insurance, to see the payment after conversion.
The Formula & Assumptions
Loan = project ×
(1 − down%)
Draw interest ≈ average
balance × construction
rate ÷ 12 × months
Permanent = P&I at the
permanent rate + taxes
÷ 12 + insurance ÷ 12
Rate handling varies by lender. Some lock the permanent rate at the initial closing with an extended lock, which costs more but removes the risk that rates move during a long build. Others float until completion.
Because there is one closing, the qualification happens once, up front. That protects you if your income situation changes during construction, which a two-loan structure does not.
Florida insurance during the build is a builder\u2019s risk policy rather than a homeowners policy, and it converts at completion. Confirm who carries it and what it costs, since it is often overlooked in the budget.
Frequently Asked Questions
Is one closing really cheaper?
Usually yes. A single closing means one set of origination, title and recording costs rather than two, which on a Florida build commonly saves several thousand dollars against a construction loan plus a separate refinance.
Can I lock the permanent rate before the build starts?
Many lenders offer an extended lock covering the construction period, sometimes with a float-down if rates improve. It costs more up front and removes the risk of finishing into a higher-rate market.
What if the build costs more than planned?
Overruns above the contingency generally come out of pocket, because the loan was sized at closing. This is why a realistic contingency matters more here than on almost any other loan type.
Do I need to qualify again at conversion?
Typically no, which is the structural advantage. You qualify once at the initial closing, so a change in employment or income during the build does not put the permanent financing at risk.
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Rates are illustrative only. APR and payments vary by credit score, loan amount, and market conditions. Subject to credit approval. Not a commitment to lend. NMLS# 1859012. Equal Housing Lender.
It estimates a single-close construction loan that converts into a permanent mortgage when the build finishes, with one set of closing costs instead of two.
Construction to Permanent Calculator in Florida
Single-close financing suits Florida builds where the timeline is uncertain, because it removes the risk of failing to qualify for the permanent loan months later. That matters if your income varies, and it matters if insurance costs rise during the build and change your qualifying ratios.
How the Construction to Permanent Calculator Works
The calculator models interest-only payments on the drawn balance through construction, then the amortizing payment at the permanent rate once the loan converts.
The Construction to Permanent Formula, Explained
Construction phase = drawn balance × (rate / 12); permanent phase = standard amortizing payment
One closing covers both phases. That saves a second set of title, origination, and recording costs, which on a large build is a meaningful sum.
The permanent rate is usually set or capped at the first closing. That protects you if rates rise during the build and limits the benefit if they fall.
The Complete Construction to Permanent Calculator Guide
The single close is the whole point. A two-loan structure means qualifying twice, and anything that changes in between, from rates to your income, can leave a finished house without permanent financing.
The cost of that certainty is flexibility. The lender fixes or caps your permanent rate early, so a large fall in rates during a long build benefits you less than a separate refinance would.
Compare the total cost rather than the rate. One closing against two is often worth a slightly higher permanent rate, particularly on builds running past six months.
Construction to Permanent Calculator FAQ
Is my permanent rate locked at the first closing?
Usually set or capped then, with some programs offering a one-time float-down if rates fall. Ask specifically, because the terms vary by lender.
How is this different from a standard construction loan?
A standard construction loan ends at completion, and you refinance it separately. This one converts automatically, so you qualify and close once.