Mortgage Payment Scenario Builder

A broker-grade mortgage payment scenario builder for client explanation, side-by-side comparison, and presentation-ready outputs. Model principal and interest, taxes, insurance, and HOA in one place, inspect amortization over time, and show structured payment differences without relying on rough estimates.

Educational and presentation use only. Runs locally in the browser with no accounts and no stored client data. Not a Loan Estimate (LE), Closing Disclosure (CD), underwriting engine, or personalized financial, lending, tax, or legal advice.

Purchase price used to compute loan amount and (optionally) taxes when using a tax rate.
Down payment ($ / %)
Use either $ or %. The unused field will lock automatically and can be updated for reference.
Converted to a monthly rate as APR ÷ 12 in this model (simplifying convention).
Converted to months (years × 12) for amortization.
Enter annual property taxes or a tax rate. The unused field will lock automatically.
Use this if you know the yearly tax bill.
If used, monthly taxes = (home price × rate%) ÷ 12.
Converted to monthly as annual ÷ 12.
HOA is included here for planning clarity (often billed separately).

Key Results

Breakdown of your estimated monthly payment (PITI + HOA).
Loan: —
LTV: —
P&I (monthly)
—
Loan payment only (fixed-rate amortization estimate).
Property taxes (monthly)
—
Estimated escrow portion for taxes.
Insurance (monthly)
—
Estimated escrow portion for insurance.
HOA (monthly)
—
Included for total-cost planning.
Total monthly (PITI + HOA)
—
This is the monthly “all-in” estimate shown by this tool.
Total interest (loan only)
—
Sum of modeled interest across the loan amortization schedule.
Educational estimates only. Results depend on your inputs and a simplified fixed-rate amortization model (APR ÷ 12 with standard rounding). Real mortgage servicing and escrow practices can differ by lender, jurisdiction, and timing rules. This tool is for understanding mechanics and comparing scenarios, not reproducing a lender statement.
Estimated Monthly Housing Cost
—
Total monthly estimate (PITI + HOA). Educational estimate for explanation and comparison.
Item
Monthly
Principal & Interest
—
Property Taxes
—
Insurance
—
HOA
—
Loan amount —
LTV —

Month Inspector

Inspect the loan amortization at any month.
Month —
Beginning Balance
—
Payment (P&I)
—
Principal (this month)
—
Interest (this month)
—
Cumulative interest
—
Remaining months (est.)
—
Month — Use the slider to inspect a month.
Early in the schedule, interest is typically higher because it’s computed on a larger balance. Over time, principal share grows as the balance declines.

Understanding Scenario Impact

Mortgage scenario modeling allows borrowers and advisors to explore how different loan assumptions influence the structure of a housing payment. While the monthly payment is often the most visible number, changes to the interest rate, down payment, and loan term can influence several aspects of the loan simultaneously.

For example, a higher interest rate may increase the monthly principal and interest payment, but changes in down payment can affect the loan amount and loan-to-value ratio. Adjusting the loan term can also shift the balance between monthly affordability and total interest paid over time.

Comparing two scenarios side-by-side makes it easier to isolate these effects. By adjusting one assumption at a time, borrowers can see how the loan structure responds and better understand the tradeoffs between payment size, total interest, and long-term financial flexibility.

The goal of scenario modeling is not to predict a final loan structure, but to illustrate how different assumptions interact so borrowers can make more informed decisions during the mortgage planning process.