Construction Loan Calculator – Estimate Interest-Only Payments & Draw Schedule
🏗️ Construction Loan Calculator Interest-Only
Estimate draw payments, interest reserves, and permanent loan conversion costs
📋 Loan Details
📊 Construction Draw Schedule
Phase 1 - Site Prep/Foundation:15%
Phase 2 - Framing/Roof:20%
Phase 3 - Rough-ins (MEP):25%
Phase 4 - Insulation/Drywall:20%
Phase 5 - Finishes/Trim:15%
Phase 6 - Final/Punch List:5%
Total: 100% (should equal 100%)
Construction Loan Summary
Total Loan Amount
$400,000
Avg Monthly Payment
$1,875
Total Interest Paid
$18,750
Final Loan Balance
$418,750
📋 Construction Phase Breakdown
Construction Cost:$400,000
Down Payment:$100,000
Loan Amount:$400,000
Origination Fees:$4,000
Average Draw Balance:$250,000
Monthly Interest Payment:$1,562
Total Construction Interest:$18,750
Total Project Cost (with interest):$518,750
📊 Draw Schedule & Monthly Payments
| Phase | Draw Amount | Cumulative Drawn | Monthly Interest |
|---|
🏗️Before you calculate your construction loan, understand this — it can significantly impact your total cost….
I learned this lesson the hard way. When I built my first custom home, I thought the construction loan was simple — borrow $400k, pay interest on the full amount. I didn't understand draw schedules or interest reserves. I ended up paying $15,000 more in interest than I budgeted because I didn't factor in how draws work.
That's when I learned: construction loan estimating isn't just total cost × rate. Here's what most people get wrong:
- You only pay interest on money drawn — Not the full loan amount. Monthly payments start low and increase as draws happen
- Draw schedules affect total interest — Front-loaded draws (foundation, framing) mean higher payments earlier
- Interest reserves cost more long-term — Rolling interest into the loan adds 15-25% to total interest paid
- Origination fees aren't optional — 1-2% of loan amount adds $4,000-8,000 to your costs
This calculator handles all of it — draw schedules, interest-only payments, origination fees, and construction-to-permanent conversion. Enter your project details, get accurate estimates you can take to lenders.
📖 How to Use This Construction Loan Calculator
- Select loan type — Standard Construction, Interest Reserve, Construction-to-Permanent, or Renovation
- Enter project costs — Construction cost, land value, down payment percentage
- Set interest rate and term — Construction loan rates are typically 0.5-1.5% higher than mortgages
- Adjust draw schedule — Set percentage of funds released at each construction phase
- Click calculate — Get loan amount, monthly payments, total interest, and final balance
💡 Pro tip: Add 10-15% contingency to your construction cost. Lenders require it, and unexpected costs always arise.
📋 Real-World Construction Loan Examples
🏠 $300k Home Build
20% down, 12 months, 7.5% rate → Monthly payments: $1,200-$2,800 → Total interest: ~$18,000
🏘️ $500k Custom Home
25% down, 15 months, 8% rate → Monthly payments: $2,500-$5,500 → Total interest: ~$45,000
⚠️ My Costly Mistake
Ignored draw schedule impact on $400k loan → $15,000 extra interest
💡 5 Construction Loan Tips I Wish I Knew
- Add 10-15% contingency to your budget. Lenders require it, and unexpected costs always arise during construction.
- Negotiate the draw schedule. Front-loaded draws increase interest costs. Ask for draws aligned with actual progress.
- Compare multiple lenders. Construction loan rates vary by 1-2% between banks. Shop around.
- Understand the inspection process. Lenders inspect before each draw. Delays in inspections delay your construction.
- Consider a construction-to-permanent loan. One closing saves $1,000-3,000 in fees vs two separate loans.
⚠️ IMPORTANT NOTE: Construction loan rates and terms vary significantly by lender, credit score, down payment, and market conditions. This calculator provides estimates for planning purposes only. Always consult with multiple lenders and review your loan agreement carefully before signing.
Frequently Asked Questions
How do construction loans work?
Construction loans provide funds in draws as work progresses. During construction, you pay interest only on the amount drawn. After completion, the loan either converts to a permanent mortgage or must be paid off. Typical construction period is 6-12 months.
How are construction loan payments calculated?
Payments are interest-only on the amount drawn to date. Monthly payment = (Outstanding balance × Annual rate) ÷ 12. As draws increase, payments increase. Some lenders offer interest reserves that roll interest into the loan balance.
What is the typical interest rate for construction loans?
Construction loan rates are typically 0.5-1.5% higher than conventional mortgages. Current rates: 6-10% depending on credit score, down payment, and lender.
What down payment is required for a construction loan?
Down payment requirements: Conventional: 20-25%, FHA: 3.5%, VA: 0% for eligible veterans, USDA: 0% in rural areas. Down payment is based on total project cost.
What is an interest reserve on a construction loan?
An interest reserve is a portion of the loan set aside to pay interest during construction. This allows borrowers to avoid monthly payments while building. Interest is added to the loan balance rather than paid out of pocket.
Nasir Badar:
Founder & Construction Estimation Expert
With 10+ years in excavation, concrete, and site work, Nasir helps contractors and homeowners create accurate real-world estimates.