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Construction Loan Calculator

Estimate your construction loan payment before you build. Enter your project cost, down payment, and rates to see the interest-only payment during the build, the construction-phase interest, and your permanent mortgage payment after the loan converts.

Estimate only. Construction funds release in stages ("draws"), so you pay interest only on what has been disbursed — the average build payment is roughly half the full-draw amount. Rates, terms, and draw schedules vary by lender.

How a construction loan payment works

A construction loan releases money in stages as the home is built, and you pay interest only on the funds drawn so far. Early in the build little is drawn, so payments are small; they rise as construction progresses. Over the whole build, your average payment is roughly half the full-draw interest-only payment. When the home is complete, a single-close construction-to-permanent loan converts to a normal principal-and-interest mortgage — the "permanent payment" shown here.

Learn more in our construction loans in California guide and the construction loan program. Building an ADU? See ADU financing.

Construction Loan Calculator FAQ

How is a construction loan payment calculated?

During construction you pay interest only on the funds drawn so far: drawn balance × annual rate ÷ 12. Because funds release in stages, your average payment over the build is roughly half the full-draw interest-only payment. After completion the loan converts to a normal principal-and-interest mortgage.

What is the interest-only payment on a construction loan?

It equals the amount drawn times the annual construction rate divided by 12. This calculator shows both the full-draw interest-only payment and the lower average payment during the build, since you only pay on what has been disbursed.

How much down payment do I need for a construction loan?

Most California construction and construction-to-permanent loans require 10–20% down, based on total project cost or the completed appraised value. Enter your percentage to see the resulting loan amount and payments.

Does this calculator include the permanent mortgage payment?

Yes. It estimates your interest-only payment during the build and your fully-amortizing principal-and-interest payment once a single-close construction-to-permanent loan converts to your mortgage.

Ready to build in California?

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