Quick Start Guide: Mortgage Payoff Calculator

Before you start

  • Know your loan amount, interest rate (APR), original term (years), and the date of your first payment.

  • Optional inputs: your regular escrow per payment (taxes/insurance/HOA) and a recurring extra payment you plan to add.

Step 1: Enter your core loan details

  • Mortgage Amount ($): The original principal (or current balance if modeling from now).

  • Interest Rate (%): Your annual interest rate, e.g., 5.25.

  • Mortgage Duration (years): Your original loan term (e.g., 30).

  • Loan Start Date: When the first scheduled payment is/was due.

Tip: If you’re modeling a new plan mid-loan, keep the original term and adjust the start date to your actual first payment date; the schedule will still show the path forward based on your inputs.

Step 2: Choose your repayment frequency

  • Monthly (12 payments/year): Standard schedule.

  • Bi-Weekly (26 payments/year): Splits your monthly payment into two every two weeks, effectively adding about one extra monthly payment each year, shortening the timeline.

Step 3: Add optional extras

  • Escrow (per payment): Amount your lender collects for taxes/insurance/HOA. Including it helps you see true cash outflow but doesn’t reduce principal.

  • Additional Payment (per payment): Extra principal you’ll add to each scheduled payment. Even small recurring extras can save thousands in interest.

  • Additional Payment Start Date: When your extra principal begins. You can set it to the next payment or a future date.

Step 4: Calculate

  • Press Calculate to update results. If you change inputs later, the button will highlight pending changes—press Calculate again to refresh.

Read your results

  • Mortgage Snapshot:

    • Base Mortgage Payment (P&I): Your standard principal + interest payment without extras.

    • Additional Payment and Escrow: What you’ve set to add each cycle.

    • Target Payment (P&I + Extra) and Total w/ Escrow: What you’ll actually pay when extra is active.

    • Payoff Timeline and Date: How long until the loan is paid off and the estimated completion date.

    • Total Interest, Total Additional, Total Escrow, Total Paid: Lifetime figures to compare scenarios.

  • Chart: Remaining Balance and Cumulative Interest over time. Watch how extra payments steepen the balance decline and flatten interest growth.

  • Amortization Schedule: Line-by-line breakdown of each payment, showing interest vs. principal, extra principal, escrow, total outflow, and remaining balance.

How to compare strategies

  • Scenario A: Monthly, no extra. Calculate and note payoff time and total interest.

  • Scenario B: Monthly, +$100 extra. Calculate again—compare interest saved and months shaved.

  • Scenario C: Bi-weekly, same extra. Calculate to see further acceleration.

Rules of thumb

  • Start small, start early: Even $50–$100 extra per payment meaningfully cuts interest.

  • Bi-weekly helps most when combined with consistent extra principal.

  • Keep an emergency fund—don’t over-commit extra payments at the expense of liquidity.

Next steps

  • Experiment with different extra amounts and start dates.

  • Revisit after rate changes or refinancing to update assumptions.