English
Start free

Build phase · permanent payment

A construction loan calculator for lenders' websites: build-phase interest and the payment after conversion

It adds land and construction cost into a total project cost, subtracts the borrower's cash or land equity, and estimates interest during the build plus the permanent mortgage payment after conversion. For a loan officer, it shows the size of the loan, how much equity the borrower brings and whether they understand carrying costs before the house exists.

Someone pricing a custom build is months from closing and already deciding which lender to trust with the longest, most complicated file you will work this year.

  • 7 inputs
  • 6 results
  • Included on every plan
  • 6 languages
Live calculator

This is the calculator your visitors use. Enter numbers to see it work.

What does a borrower want to know before building a home?

Usually two numbers: what it costs to carry the loan while the house goes up, and what the mortgage payment looks like once they move in. Builders quote construction costs; few explain financing.

Take $100,000 of land, a $400,000 build and $100,000 of equity. The equity covers the land first, so $400,000 is borrowed. At 8.5% over a 12-month build with funds drawn evenly, interest during construction runs about $17,000, or roughly $1,417 a month on average. After conversion at 6.75% over 30 years, the payment is about $2,594. The quiet worry is paying rent, or an existing mortgage, alongside those interest-only payments, and what happens if the build runs late.

How do loan officers use a construction calculator to win builder business?

This is a relationship tool as much as a lead tool. Put it on a page you can hand to builders and land sellers, a co-branded new-construction landing page, or a guide for buyers who already own a lot. Builders appreciate a lender whose page explains draws and carrying costs, because it cuts their own sales cycle. Keep any builder arrangement at fair market value, and check co-marketing terms with compliance.

Construction leads have long timelines but high intent. Read the submission for the Down Payment / Equity figure: land the borrower already owns counts here and often settles the equity question. Then check the Construction Period. Twelve months or more means a full custom build; six months or less may be a builder's spec home with a tighter schedule.

The lead lands in the built-in CRM with every number they entered, so you can prepare questions about the builder, the plans, the budget contingency and whether they need a one-time-close product. Pair the page with the affordability calculator for borrowers who have not yet set a budget, and tag construction submissions with a dedicated HighLevel workflow built around a longer nurture.

What arrives in your CRM

What the numbers tell you about the borrower

  • Down Payment / EquityA large figure often means the borrower owns the land outright. That simplifies equity and makes the file far more workable; ask early whether the lot is paid off and when it was bought.
  • Construction Period (months)Long periods mean a custom build with more draw risk and a longer runway to closing. Short ones suggest a production builder. Your follow-up cadence should match the timeline, not your monthly volume target.
  • Avg Monthly Interest-Only Payment (build)Compare this with whatever housing cost they carry today. If they will pay both at once, cash flow and reserves become the real qualifying question, and you should raise it before they sign a build contract.
  • Total Project CostThis shows the scale of the project and hints at the program: a total above the conforming limit points toward jumbo or portfolio construction financing, which changes equity and reserve expectations.
  • Construction Rate (%)A construction rate typed equal to the permanent rate suggests the borrower has not been quoted yet. That is an opening to explain how build-phase pricing differs and why lender choice matters early.

A first message that uses their numbers

What should your first message to a construction lead cover?

Thanks for running your build numbers. Construction financing depends a lot on the builder, the plans and how the land is held, so a short call to understand your project would help me explain the options. Do you already have a builder and a target start date?

Explain that conversion terms, draw schedules and rate locks vary by program; do not quote a permanent rate as fixed for a home that has not been built.

Where this calculator earns its place

  1. 01

    Builder co-branded landing page

    Builders can send prospects to a page that explains financing, and you capture the buyer at the start of the project.

  2. 02

    Land or lot purchase guide

    Buyers who already own land are among the most qualified construction prospects and search for this exact calculation.

  3. 03

    New construction section of your website

    Visitors comparing building with buying need a tool that shows carrying costs, which a standard payment calculator cannot.

Limits worth knowing

  • It assumes funds are drawn evenly, with about half outstanding on average; a front-loaded draw schedule raises actual interest.
  • Construction-period interest is shown separately and is not added to the loan amount, though some programs do finance it.
  • Cost overruns, permits outside the builder's contract and closing costs are not included, and contingencies matter on every build.

Calculator disclaimer: Estimates only. Construction interest assumes any financed land is outstanding from day one and build funds are drawn evenly (about half outstanding on average); your real draw schedule will differ. Confirm terms and conversion details with your lender.

Definitions in the calculator

Construction loan
A short-term loan that funds building a home, paid out in stages as work is completed rather than as one lump sum. During the build, the borrower usually pays interest only on the amount drawn so far. This calculator estimates that build-phase interest separately from the permanent mortgage that follows.
Construction-to-permanent loan
A single loan that covers the build and then converts to a standard mortgage once the home is finished, often with one closing. The permanent rate and term entered here set the monthly payment after conversion. Conversion rules, rate locks and fees differ by lender, so the details are worth confirming before the build starts.
Draw schedule
The plan for releasing construction funds in installments, usually after inspections confirm each stage is done. Interest accrues only on money already drawn. This calculator assumes build funds are drawn evenly, so about half is outstanding on average, while any financed land is outstanding from day one. A real schedule will produce different interest.
Interest-only payment
A payment that covers the interest due but repays no principal, so the balance does not fall. Construction loans typically require interest-only payments during the build. The average monthly interest-only payment shown here is the estimated construction-period interest divided by the number of months in the build.
Total project cost
The land cost plus the construction cost. It is the figure your down payment or equity is measured against and the starting point for the loan amount. It excludes construction-period interest, closing costs, permits handled outside the builder’s contract and cost overruns, all of which can add to what the project actually requires.
Down payment / equity
Cash or the value of land you already own that you put toward the project. This calculator applies it to the land first and then to construction; the rest is borrowed. Lenders set minimum equity requirements for construction loans, and land already owned outright can often count toward it.
Loan amount
Total project cost minus your down payment or equity. It is the balance that accrues interest during construction and then becomes the permanent mortgage. Construction-period interest is shown separately and, in this calculator, is not added to the loan, so it represents cash paid during the build.
Permanent loan rate
The annual interest rate on the mortgage that replaces the construction loan after the home is finished. Construction rates are usually higher because the lender is financing an unfinished property. Together with the permanent term and loan amount, this rate sets the long-term monthly principal-and-interest payment and the total interest on the permanent loan.
Amortization
The schedule by which each permanent-loan payment is split between interest and principal until the balance reaches zero. Amortization starts only after conversion; during construction nothing is repaid. Early permanent payments are mostly interest, which is why total interest on the permanent loan can approach or exceed the amount borrowed on a long term.

Terms on this page

Pairs well with

FAQ · 8 questions

Questions about this calculator

How is interest calculated during construction?

Interest is charged only on money that has been drawn. The calculator treats any financed land as outstanding from day one and assumes build funds are drawn evenly, so about half the construction balance is outstanding on average. It multiplies that average by the construction rate over the build period. Your lender's actual draw schedule will move the real figure up or down.

Does land I already own count toward the down payment?

In many construction programs it can, and that is how this calculator treats it. Enter the land's value as part of Down Payment / Equity; the tool applies equity to the land first, then to construction. Lenders set their own rules on how owned land is valued, how long it must have been held and what documentation is needed.

Why is the construction rate higher than the permanent rate?

The lender is financing a property that does not exist yet, so the risk is higher until the home is finished and converts to a standard mortgage. Construction loans are also short-term and need more oversight, including inspections before each draw. Once the house is complete, the permanent rate you enter drives the long-term payment.

What is a construction-to-permanent loan?

It is a single loan that funds the build and then converts to a standard mortgage when the home is finished, often with one closing. The calculator models both phases: interest-only payments during construction and a fully amortizing payment after conversion. Rate locks, conversion fees and qualification rules vary by lender, so confirm how each program handles the switch.

Why should a loan officer offer a construction calculator at all?

Because construction borrowers pick a lender early and stay for months, and many builders steer clients toward lenders who explain financing well. A calculator that shows carrying costs gives you a reason to be on builder and land-sale pages. The leads are fewer than purchase leads but larger and more committed. A single closed construction loan can also lead to referrals from the same builder.

How long is the follow-up window for construction leads?

Longer than a typical purchase. Some borrowers are still choosing a builder or finalizing plans, so closing may be several months away. A quick first touch matters as much as ever, but plan a longer nurture with useful check-ins tied to their milestones, such as plan approval or permit issuance, rather than weekly rate updates.

Can builders embed this calculator on their own website?

The calculator embeds with one line of code on any site, so a builder partner could host it, with leads still delivered to your account. Before doing that, settle the arrangement with compliance, since referral relationships with builders fall under RESPA. Keep co-marketing at fair market value and make sure your NMLS ID and required disclosures appear.

Does the calculator check construction loan eligibility?

No. It estimates costs and payments from what the borrower enters. It does not check credit, income, reserves, the builder's qualifications or the appraisal, all of which a construction lender reviews. It is a pre-qualification conversation starter, not an approval, and the borrower's real terms depend on the program and full underwriting. Builder approval in particular varies by lender, so raise it early.

PrequalFunnel

Put the Construction Loan Calculator on your site today

Brand it, embed it with one line, and get every lead with the borrower's numbers attached.

Free forever on Originator. Upgrade when you want webhooks and your own brand. 14-day free trial on monthly and yearly. Cancel before it ends and you pay nothing.