Tools
Mortgage Payoff Calculator
Enter your current mortgage and add any combination of extra-principal strategies — monthly, annual, twice-yearly, one-time, or biweekly — and the calculator builds two complete month-by-month amortization schedules: the payoff you are on, and the payoff you could be on.
Quick Answer
Additional principal payments reduce your outstanding mortgage balance, which can shorten the time required to repay the loan and reduce future interest. The impact depends on your remaining balance, interest rate, payment amount, timing, and how much additional principal you pay.
Current mortgage
Principal and interest only — exclude property taxes, homeowners insurance, HOA dues, mortgage insurance, and escrow.
Quick scenarios
Presets are optional shortcuts. You can edit any field below afterward.
Accelerated payoff strategy
One-time extra principal
Add a dated lump sum — a bonus, a tax refund, or proceeds from a sale — to model its effect on the payoff date.
You could pay off your mortgage
6 yrs 2 mos sooner
Estimated payoff moves from February 2000 to December 1993.
Estimated interest saved
$136,254
Current payment plan
- Estimated payoff
- February 2000
- Time remaining
- 30 yrs 1 mo
- Remaining interest
- $574,180
- Total remaining payments
- $1,024,180
Accelerated plan
- Estimated payoff
- December 1993
- Time remaining
- 23 yrs 11 mos
- Remaining interest
- $437,926
- Total remaining payments
- $887,926
- Total extra principal applied
- $71,698
Payoff timeline
6 yrs 2 mos sooner under the accelerated plan.
Want to Compare Paying Down Your Mortgage Against Another Strategy?
Extra principal is one option among several — recasting, refinancing, using equity, or keeping the cash liquid can all change the picture. Send Jonathan the scenario you just modeled and he can walk through the trade-offs with you.
Prefer to talk? Call Jonathan at 210-993-5023
Balance over time
Remaining principal at the end of each calendar year under both plans.
Why extra principal changes the math
Mortgage interest is calculated against the outstanding principal balance. When an additional payment reduces that balance, every future month’s interest is calculated against a smaller number. Over time this can shorten the payoff period and reduce the total interest paid, because more of each scheduled payment goes to principal instead of interest.
Extra principal is not automatically the best use of cash. Before committing to a payoff strategy, it is worth weighing:
- Emergency reserves and general liquidity needs
- Higher-interest debt that may cost more than the mortgage rate
- Other investment or savings opportunities
- Your mortgage rate relative to other uses of the money
- How long you expect to keep the property
- Tax considerations specific to your situation
This is general education, not individualized investment or tax advice. Consult your own tax or financial professional about your circumstances.
Before you send extra money
Before making additional payments, confirm with your mortgage servicer that additional funds will be applied to principal and review any applicable loan terms or prepayment restrictions. Servicers do not all process additional payments the same way — some apply extra funds to the next scheduled payment rather than to principal unless instructed otherwise.
Assumptions used
- Interest accrues monthly on the outstanding balance at one twelfth of the annual rate entered.
- Additional principal is applied in the month it occurs and reduces the balance before the following month's interest is calculated.
- Extra payments are treated as principal reductions, not as prepaid future monthly payments.
- The final payment is capped at the remaining principal plus that month's interest, so the balance never goes below zero.
- Only principal and interest are modeled. Taxes, insurance, HOA dues, and mortgage insurance are excluded.
- Biweekly scenarios are modeled as the mathematical equivalent of 13 monthly payments per year, not as a servicer program.
- Example values are pre-filled for demonstration. They are not current market rates.
Results are estimates for educational purposes only and are based on the information and assumptions entered. They are not a loan approval, commitment to lend, or rate quote. Actual loan terms, payments, eligibility, taxes, insurance, and other costs may differ.
Payoff dates, interest totals, and savings shown here are estimates based on the balance, rate, payment, and extra-payment assumptions you entered. Your actual loan may include fees, escrow, rate adjustments, or prepayment terms that change the result.
Cascada Mortgage Advisors, Inc. DBA HomeFlow (NMLS #2470941, CA DRE #02206556) is a licensed mortgage broker, not a direct lender. Any interest rate you enter is your own assumption, not a HomeFlow rate.
What this calculator does
It runs two independent amortization schedules from the same starting point: your current plan with no additional principal, and an accelerated plan that adds the extra payments you enter. Comparing them shows the payoff date under each plan, the time remaining, the interest still owed, the total remaining payments, and the interest the accelerated plan is modeled to save.
How extra principal changes the math
Mortgage interest is calculated against the outstanding principal balance. When an extra payment reduces that balance, every future month's interest is calculated against a smaller amount, so more of each scheduled payment goes to principal. The effect compounds over the life of the loan, which is why modest extra payments early can move the payoff date by years.
Strategies you can combine
- Additional principal every month — a fixed amount on top of the scheduled payment.
- An annual extra payment in a chosen month — a year-end bonus or tax refund, for example.
- Two extra payments per year in chosen months.
- One or more dated one-time lump sums.
- A biweekly model, equivalent to 13 monthly payments per year.
Before you send extra money
Extra principal is not automatically the best use of cash — emergency reserves, higher-interest debt, other opportunities, liquidity needs, your rate, and how long you expect to keep the property all matter. Before making additional payments, confirm with your mortgage servicer that additional funds will be applied to principal and review any applicable loan terms or prepayment restrictions. Servicers do not all process additional payments the same way.