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Enter your current mortgage. Build scenarios — extra payments, lump sums, recasts, refinances. See exact savings, payoff dates, and break-even points, side by side.
Extra PaymentsLump Sum + RecastRefinance AnalysisBreak-EvenUp to 5 Scenarios
Your Current Mortgage
$
What you owe today, not the original amount.
%
Unusually low — double-check
yr
$
Principal + interest only — not escrow or insurance.
Enter your start date and original term to auto-calculate remaining term.
Build Your Scenarios
Each scenario starts from your current mortgage. Add events to model what happens if you take action. Mix and match — extra payments, a lump sum + recast, a refinance, or all of the above.
Results
Scenario Comparison
Side by Side
Remaining Balance Over Time
Balance Paydown
Remaining principal each month — all scenarios vs baseline.
Amortization Detail
How This Works
Concept 01
Why Extra Principal Payments Work So Well
Every dollar you pay above your scheduled payment goes directly to principal. That reduces the balance on which next month's interest is calculated.
Because mortgage interest compounds monthly, reducing the balance early has a multiplied effect — the savings grow larger the earlier you start.
On a $350k mortgage at 6.5%, an extra $200/month can save over $60,000 in interest and cut 4+ years off the loan.
Concept 02
What Recasting Is (and When to Use It)
Recasting means paying a large lump sum to your lender, who then recalculates your monthly payment based on the lower balance — using your same interest rate and remaining term.
Unlike a refinance, a recast does not create a new loan, does not require a credit check, and typically costs just $150–$500. The trade-off: your rate and term don't change.
Recast if you want a lower monthly payment without resetting your term or paying refinance closing costs.
Concept 03
Recast vs Refinance: The Real Difference
A recast keeps everything the same (rate, term) and just recalculates your payment on a lower balance. Fast, cheap, no credit check.
A refinance is a brand new loan. You can get a lower rate, change your term, or cash out equity — but you pay closing costs and restart the amortization clock.
Recast = lower payment on same loan. Refinance = new loan, new rate, new clock.
Concept 04
Lower Payment ≠ Lower Total Cost
Refinancing to a lower rate can reduce your monthly payment — but if you extend the term or roll in closing costs, you may pay significantly more in total interest over the life of the loan.
This is why break-even analysis matters. A refi that saves $200/month but costs $8,000 upfront takes 40 months to break even — and might not be worth it if you plan to sell sooner.
Always compare total cost (interest + fees), not just monthly payment.
Concept 05
What Refinance Break-Even Means
Break-even is the point where your cumulative monthly payment savings equal the upfront cost of the refinance. Before that month, you're still "in the hole."
If you plan to sell or refinance again before break-even, the refinance costs you money on net — even if the new rate is lower.
The engine uses a precise month-by-month amortization model — not rounding approximations. Projections are accurate for fixed-rate mortgages with no escrow changes. Results will differ from your actual payoff if your lender applies payments differently, if you have an adjustable rate, or if your escrow fluctuates. Use these numbers for comparison and decision-making, not as a guarantee.
No. Everything runs in your browser. No data is sent anywhere. Nothing is stored. You can use this tool completely anonymously.
Remaining term is how many months are left on your current mortgage. If you started a 30-year loan in January 2020, you have roughly 25 years and 3 months remaining as of March 2026. You can also find the exact remaining term on your most recent mortgage statement or by calling your lender.
This calculator uses "months from now" (Month 0 = your next payment, Month 24 = 2 years from now) for event timing. The calculated payoff dates are shown as calendar months in the results. The hint text under each event's month field shows the approximate calendar date.
That depends on your mortgage rate, expected investment returns, tax situation, and risk tolerance. If your mortgage rate is 6.5% and you expect a 7–10% long-term market return, the math slightly favors investing — but risk-adjusted, many people prefer the guaranteed return of paying off debt. Neither answer is wrong. What matters is making the decision with real numbers, not gut feeling. This calculator gives you the debt side of that equation.
Yes. Each scenario supports any combination of events — extra monthly payments, multiple lump sums (with or without recast), and a refinance. The engine processes them in chronological order. You could model, for example: an extra $500/month starting now, a $20,000 lump sum with recast in year 2, then a refinance in year 5.