Compare amortizing and drawn-balance payments
Compare two transparent payment mechanics using your own assumptions. These are illustrations, not current offers, rate averages, approvals, or all-in borrowing costs.
An open-end line secured by home equity. Draw-period payments are based on the current balance; rates and payment rules vary by plan.
Current drawn balance × entered annual rate ÷ 12. A real variable rate can change this payment.
Monthly interest × months in the illustration. It excludes future draws and rate changes.
The model pays no principal, so the entered drawn balance remains due after the illustration period.
Illustrations only. Excludes closing and origination costs, taxes, insurance, mortgage insurance, escrow, variable-rate changes, draw and inspection fees, and interest reserves. Confirm the full terms and disclosures with a licensed lender. RSA Development does not provide financial advice.
Payment breakdown
This scenario pays interest during the selected period and leaves the drawn principal outstanding.
No principal is repaid in this illustration.
What the lender earns over the life of the loan.
12 monthly installments over 1 years.
What this model does — and does not do
Verified September 24, 2026. Federal consumer guidance distinguishes fixed-rate amortization from open-end HELOC draws and construction-phase advances. Product contracts vary, so this tool keeps every number user-entered and does not estimate approval, available equity, future rate changes, or total project financing.
FAQ
Frequently asked questions
What homeowners ask before choosing a loan product to fund an LA ADU.
Which loan product is best for an LA ADU?
HELOCs, construction loans, renovation loans and cash-out refinancing have different draw rules, collateral, rate exposure and qualification requirements. A licensed lender should compare current terms against the project schedule and the owner’s broader financial position.How accurate are the rates in this calculator?
The calculator does not supply current rates. Its editable default is only an illustration, not an offer or market average. Enter a lender quote or your own assumption, then confirm rates, fees, draw rules, payment changes and qualification directly with a licensed lender.Can I include the ADU rental income in my qualifying ratio?
Treatment of projected rent varies by lender and loan product. Ask a licensed lender what documentation is required, how much projected income may be considered and whether the underwriting changes before and after completion.Are there any fees this calculator doesn't show?
Loan estimates may omit origination, title, appraisal, recording, inspection, draw and extension charges. Request a complete fee schedule from the lender and include those costs in the project scenario before comparing products.Does the calculator model a complete construction-to-permanent loan?
No. The interest-only scenario illustrates accrued interest on a current drawn balance. The amortizing scenario separately illustrates a permanent-phase principal-and-interest payment. It does not predict a draw schedule, conversion balance, rate change, interest reserve or lender fees.HELOC vs renovation loan vs cash-out — which fits an ADU best?
There is no universal best product. Compare collateral, draw access, variable-rate exposure, repayment changes, replacement of an existing mortgage, fees and project timing. Ask licensed lenders for product-specific disclosures using the same project assumptions.Is the CalHFA ADU Grant currently available?
No open round was shown when checked September 24, 2026. CalHFA's official ADU page says the latest funding round was fully allocated on December 28, 2023 and warns consumers about claims that someone can obtain the grant. Treat it as a closed grant program unless CalHFA publishes a new application window.