Model extra monthly payments, a one-time lump sum, and biweekly payments — together, not one at a time — and see the exact interest saved and new payoff date. No signup, full amortization schedule shown below.
$0in interest saved
New payoff date
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Time saved
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Standard payment
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New vs. standard payoff time
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Standard payoff time (no extra payments)—
Total interest — with extra payments$0
Total interest — standard schedule$0
Year-by-year payoff schedule
Year
Principal paid
Interest paid
Remaining balance
Full amortization schedule
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Principal
Interest
Balance
How this is calculated
This calculator runs a full period-by-period amortization simulation — not a shortcut formula — so extra monthly payments, a lump sum, and biweekly payments can all be modeled together instead of one at a time, which is where most mortgage calculators stop short.
Standard paymentCalculated from your balance, rate, and remaining term
Extra monthly paymentApplied directly to principal every period
Lump sumApplied to principal in the first payment period
Biweekly modeHalf the monthly payment every 2 weeks — 26 payments/year (13 monthly-equivalents instead of 12)
Interest saved compares this schedule against your standard schedule with no extra payments, at the same rate and starting balance.
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Estimates only. This calculator is for educational purposes and is not financial advice. It assumes a fixed rate for the remaining term and doesn't account for refinancing, rate changes, prepayment penalties, or lender-specific rules about extra payments (some lenders require you to specify extra payments go to principal). Consult your loan servicer or a financial advisor before making payoff decisions.
Frequently asked questions
Should I pay off my mortgage early, or invest the extra money instead?
It depends on your mortgage rate versus your realistic expected investment return, and your risk tolerance. If your mortgage rate is meaningfully below what you could reasonably expect from a diversified investment over the same period, investing the difference has historically come out ahead on paper — but paying down the mortgage is a guaranteed, risk-free return equal to your interest rate, with no market volatility. Many people split the difference: pay a moderate extra amount toward the mortgage while still investing normally, rather than choosing one extreme.
Is biweekly or a fixed extra monthly payment better?
Biweekly payments work by sneaking in one extra monthly-equivalent payment per year (26 half-payments = 13 monthly payments), which is a modest, automatic acceleration. A deliberate extra monthly payment gives you more control — you can pay more (or less, in a tight month) than the biweekly schedule would force. Use the toggle above to compare both against your specific numbers; for most loans a meaningful fixed extra payment saves more than biweekly alone, but combining both saves the most.
Does my lender apply extra payments to principal automatically?
Not always. Some loan servicers apply extra payments to your next scheduled payment (effectively prepaying, not accelerating payoff) unless you explicitly mark the extra amount as "additional principal only." Check your servicer's payment portal or call them to confirm — this calculator assumes every extra dollar goes straight to principal, which only happens if your servicer is instructed to do that.
Will paying extra hurt me if I might sell or refinance soon?
If you're likely to sell or refinance within the next few years, the interest savings from extra payments shrink substantially — you're front-loading payoff of a loan you won't keep for its full term. In that case, extra funds sitting in a liquid, accessible account (rather than locked into home equity) may serve you better. This calculator shows the full-term outcome; check the year-by-year table above to see how much you'd have saved by any specific year, not just at full payoff.
Why is this calculator free with no signup?
The amortization math is standard and public. This tool runs the simulation in your browser — nothing you enter (your balance, rate, or payment plans) is sent to a server or stored anywhere.