Early Mortgage Payoff Calculator

The Early Mortgage Payoff Calculator helps you see how much faster you can become debt-free with a monthly extra or a biweekly plan. Enter your remaining balance, current APR, and months left; then test a fixed extra amount, a one-time lump sum, or both. The output puts the headline items first—new payoff date, time shaved off, and interest saved—followed by a compact summary and a snapshot of key periods. You can also download an updated amortization schedule as CSV for deeper analysis.

How the plans differ: the monthly extra keeps your usual schedule but adds principal every month. The biweekly plan splits your monthly payment in half and applies it every two weeks. Because there are 52 weeks in a year, you make 26 half-payments—roughly 13 full payments—so you sneak in one extra monthly payment per year. If you also add an extra amount, we split it across the biweekly periods. Either way, the earlier you reduce the balance, the less interest you pay across the remaining term.

Reading the results: the summary block lists your scheduled payment, the new payoff date, the number of months saved, total interest on your current path, total interest with your plan, and the savings difference. The snapshot shows Month 1, Month 6, Month 12, a midpoint, and the final period so you can sanity-check progress without scrolling a long table. The CSV includes each period’s payment, interest, principal, and remaining balance, so you can mark milestones or model a future recast or refinance.

Tips: verify that your servicer applies extra amounts to principal only and does not advance the due date unless you request it. If you receive a bonus or tax refund, test it as a one-time lump sum; paying early reduces interest from the next period onward. Keep a cash buffer—prepaying feels great, but an emergency fund matters more. Finally, if you carry high-APR revolving debt, prioritize that before accelerating a low-rate mortgage; the net savings are usually larger.

Limitations: this is an educational planner. It models principal and interest only and uses equal monthly or biweekly periods with a steady APR. It does not include escrowed taxes and insurance, daily interest differences from payment timing, late fees, or adjustable-rate changes. For an exact same-day payoff, always request a payoff statement that includes per-diem interest and any fees.

Monthly payment for principal and interest is PMT = L·r·(1+r)^n / ((1+r)^n − 1) with L loan amount, r=APR÷12, and n months. We build a baseline amortization using this PMT. For a monthly extra, each period pays PMT + extra with a one-time lump applied at the start. For biweekly, we use 26 periods per year with rate APR/26 and half-payment PMT/2 plus extra/2. Interest saved is baseline total interest minus plan total interest; months saved is baseline months minus plan months. Payoff date is today plus the computed number of periods.