Construction Calculator
Plan construction-to-permanent financing with draw schedule interest-only payments, editable permanent loan rate, and an optional PITI breakdown once the loan converts.
Get Started in 3 Steps
How to Use the Construction Calculator
Set Your Project Budget
Enter land value and total construction cost. The calculator segments these into your draw schedule and computes interest-only payments during the build.
Model the Construction Phase
Review estimated monthly interest payments during construction based on your draw timeline and construction loan rate.
Configure the Permanent Loan
Set your permanent loan rate and term to see your full monthly PITI payment once the loan converts after construction is complete.
Construction Loan Calculator
Land · Build · Permanent Financing
Project Costs
Purchase price or land value
Hard + soft build costs
Total Cost
$750,000
Down Payment
$150,000
Loan Amount
$600,000
Construction Phase
Construction Rate
Avg. Interest
during build
$1,828/mo
Permanent Mortgage
Permanent Rate
Permanent P&I
$3,597
30-yr fixed · 5.999%
Loan Amount
$600,000
Total Payments
$1,294,890
Taxes & Insurance
Property Tax
~$688/mo
Home Insurance
monthly premium
LTV
80.0%
Cash to Close
Closing costs are estimated. Contingency is held in a lender-controlled draw account and financed into your construction loan — not paid separately at closing.
Estimates only. Actual closing costs vary. Contact Lumen Mortgage for a formal construction loan analysis. NMLS #1498678.
How does a construction loan work?
A construction loan is a short-term (6-18 month) loan that funds your build in stages called 'draws.' During construction, you pay interest only on the amount drawn. Once complete, it converts to a permanent mortgage — either automatically (one-time close) or through a separate refinance (two-time close).
Best for: Custom home builders, buyers building on owned land, anyone comparing one-time vs. two-time close construction financing
How It Works
Understanding the Construction Calculator
Construction loans fund the building of a new home through a two-phase process: a short-term construction phase with interest-only payments on drawn funds, followed by conversion to a permanent mortgage. This calculator models both phases so you can budget for the full lifecycle cost.
Worked example: You're building a custom home in Ashland, Oregon. Land value: $200,000 (already owned). Construction budget: $450,000. Total project: $650,000. With 20% down ($130,000), your construction loan is $520,000 at 8.00% for a 12-month build. At 50% average draw, your average interest-only payment is $1,733/month. Once complete, the loan converts to a 30-year mortgage at 6.50%: monthly P&I of $3,287.
This calculator helps you budget for the often-overlooked construction phase interest costs. Pair with the Renovation Loan Calculator if you're remodeling rather than building new.
Ready to apply?
Numbers look right? Explore our Construction Loans page for eligibility details, rates, and next steps.
About This Calculator
What the Construction Calculator is For
Construction loans work in two phases: an interest-only draw period while the home is being built, followed by a permanent mortgage once construction is complete. This calculator models both. Set your land value and total construction budget, enter your draw schedule and construction loan rate, then configure your permanent loan terms. The result is a clear picture of your interest-only payments during the build and your full monthly PITI after conversion — including an optional property taxes and insurance overlay so nothing comes as a surprise at closing.
Common Use Cases
- Estimating interest-only costs during a new construction build
- Planning the permanent loan payment before the construction loan converts
- Modeling total project cost including land, construction, and carry costs
Ready to turn numbers into a loan?
Common Questions
Construction Calculator — Frequently Asked Questions
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From the Blog
Further Reading
OregonConstruction Lending in Ashland & Southern Oregon: Custom Builds, Construction-to-Perm, Spec Loans, ADUs & Renovation Financing
Whether you're building a custom home in the Ashland hills, adding an ADU to your Medford lot, renovating a fixer in Talent, or breaking ground on a spec build in the Rogue Valley, Southern Oregon's construction lending landscape is more nuanced than most borrowers realize. Here's a complete guide to every financing tool available for builders, developers, and homeowners in 2026.
InvestmentSpec Construction Loans in Oregon & California: Strategy, Qualification, and the Profit Calculus in 2026
Building on speculation is one of the highest-leverage plays in residential real estate — and one of the most misunderstood. Here is a ground-level look at how spec construction loans work, what lenders actually underwrite, and why the Oregon and California markets still reward disciplined builders.
All calculator results are estimates for informational purposes only and do not constitute a loan commitment or guarantee of any specific rate or terms. Actual loan terms will depend on creditworthiness, property type, and market conditions. Lumen Mortgage Corporation · NMLS #1498678 · Licensed in Oregon & California · 920 SW 6th Ave, Suite 1200, Portland, OR 97204.