Mortgage Payoff Calculator
See how extra monthly payments accelerate mortgage payoff and save tens of thousands in interest. Compare current pace vs accelerated payoff to find the right balance.
Reviewed & updated for 2026 by Rakesh Choudhary, PhD · How we calculate
Impact of extra payments, $300K mortgage at 7%
| Extra/month | Payoff in | Time saved | Interest saved |
|---|---|---|---|
| $0 (baseline) | 30 years | — | — |
| $100 | ~26 yrs | ~4 years | ~$68,000 |
| $200 | ~22 yrs | ~8 years | ~$125,000 |
| $300 | ~20 yrs | ~10 years | ~$155,000 |
| $500 | ~17 yrs | ~13 years | ~$190,000 |
| $1,000 | ~13 yrs | ~17 years | ~$240,000 |
The math behind mortgage prepayment savings
Mortgages are front-loaded with interest. On a 30-year $300,000 loan at 7%, your first payment is about $1,996, but only $246 of that goes to principal in month 1. The other $1,750 is interest. By month 360 (the last payment), the ratio is reversed: most of it is principal, almost none is interest. This curve is why extra payments early in the loan are so dramatically more valuable than later.
When you make an extra principal payment, you skip ahead in the amortization schedule. An extra $500 in month 1 effectively eliminates a future payment that would have been mostly interest. The same $500 in month 240 has much less impact because that future payment was already mostly principal.
Practical implication: aggressive prepayment in years 1-10 of a mortgage is worth far more than in years 20-30. If you have a windfall (inheritance, bonus, equity sale), it has the biggest impact applied to a relatively new mortgage. On an old mortgage near payoff, the same windfall is almost a wash with putting it in investments.
Pay off vs invest: the honest comparison
The classic question: I have $500/month extra. Should I pay down the mortgage or invest it? The technically correct answer compares the after-tax mortgage rate to the after-tax expected investment return. Mortgage rate 7%, marginal tax bracket 22%, and assuming you itemize: after-tax cost of mortgage is 7% × (1-0.22) = 5.46%. After-tax expected return on stocks (long-term): 10% pre-tax minus 15% long-term capital gains = 8.5%. Stocks win by about 3 percentage points.
But this math has caveats. Most homeowners don't itemize anymore (standard deduction is too high), so the mortgage interest deduction provides little or no tax benefit, making the full 7% rate the comparison. Stock returns are uncertain and volatile; mortgage paydown is a guaranteed 7% "return." Personal disposition toward risk matters: some people sleep better with a paid-off house than with a higher net worth statement.
The standard advice ordering: (1) Capture full employer 401(k) match first, that's a 100% immediate return. (2) Pay off high-interest debt (credit cards, personal loans above 8%). (3) Build 3-6 month emergency fund. (4) Max out tax-advantaged accounts ($24,500 401(k), $7,500 Roth IRA in 2026). (5) Then decide: extra mortgage payment vs taxable brokerage. The choice in step 5 is partly mathematical, partly personal.
Smart prepayment strategies
- Biweekly payments: Pay half your monthly payment every two weeks. Because there are 52 weeks/year = 26 half-payments = 13 full monthly equivalents, you make one extra monthly payment per year. Cuts about 5-7 years off a 30-year mortgage. Important: make sure your servicer applies each biweekly to principal as it arrives, not held in escrow.
- Round up to nearest $100 or $500: A $1,996 payment becomes $2,000 or $2,500. The extra $4-504/month directly cuts principal. Painless and accumulates.
- One extra payment per year: Use tax refund or bonus to make one extra full payment annually. Equivalent to biweekly effect.
- Refinance to shorter term: 15-year mortgages typically have rates 0.5-1% lower than 30-year. The shorter term forces faster principal paydown. Risk: monthly payment is higher, so you lose flexibility if income drops.
- Recast after large lump sum: If you receive a large windfall (inheritance, business sale), apply it as a lump sum and ask the lender to recast, re-amortize the remaining balance over the original term. Drops your monthly payment without refinancing.
- Avoid "biweekly programs" that charge fees: Some third-party companies charge $300-500 setup plus $5-10/payment to "automate biweekly." Do it yourself by writing checks or scheduling extra principal payments, same effect, zero fees.
FAQs
How much can I save by paying off my mortgage early?
Significant amounts. Example: 300,000 mortgage at 7% over 30 years = $419,000 total interest. Adding $200/month extra payment cuts the term to ~22 years and saves $125,000 in interest. Adding $500/month: ~17 years and $190,000 saved. The earlier you start, the more dramatic the savings.
Should I pay off my mortgage early or invest?
Depends on your mortgage rate vs expected investment return. If mortgage rate is 7% and you expect 7% real return on investments: roughly equal (slight tax advantage to investment, slight emotional advantage to payoff). Mortgage rate above 8%: usually favor payoff. Below 5%: usually favor investing (especially if not maxing tax-advantaged accounts).
What's the fastest way to pay off a mortgage?
Three main approaches: (1) Bi-weekly payments, pay half the monthly amount every 2 weeks = 13 monthly payments per year vs 12 = ~4-5 years sooner. (2) Round up monthly payment to next $100 or $500 increment. (3) Lump sum extra payments from tax refund, bonus, or sale of unused asset. (4) Refinance to 15-year loan, forces faster payoff.
Do all mortgages allow prepayment without penalty?
Most conventional loans allow unlimited prepayment without penalty. Some older or non-conforming loans (jumbo, certain ARMs, refis from 2008-2014) had prepayment penalties for the first 2-5 years. Read your mortgage note before making large extra payments. Federally backed loans (FHA, VA, USDA) never have prepayment penalties.
Does paying off mortgage early hurt my credit score?
Marginally. Credit score factors include credit mix (different types of accounts). Closing a mortgage reduces 'installment loan' diversity. Expect a 5-30 point temporary dip after payoff. Not enough to matter unless you're actively shopping for a new loan.
Should I make biweekly mortgage payments?
Mathematically equivalent to adding 1 extra monthly payment per year. The 'biweekly trick' works because there are 52 weeks/year = 26 biweekly payments = 13 monthly payments. Saves about 5-7 years on a 30-year mortgage. WARNING: many lenders offer 'biweekly programs' that just hold your payment in escrow then make 12 monthly payments. Make sure they apply each biweekly to principal.