Biweekly Mortgage Payment Calculator
Calculate how biweekly mortgage payments save interest and shorten your loan term. See years saved and total interest reduction compared to monthly payments.
Extra Mortgage Payment Calculator
See how extra mortgage payments reduce your loan term and save interest. Model one-time, monthly, or annual extra payments and compare to your original schedule.
$
%
Extra Payments
Added each month
$
Once per year
$
Applied immediately
$
Original vs Extra Payments
Original Schedule
Monthly Payment⧉
$1,896.20
Principal + interest per month
Total Interest⧉
$382,633.47
Total interest over loan life
Payoff⧉
30.0 years
With Extra Payments
Effective Payment⧉
$2,096.20
Total Interest⧉
$279,184.67
Total interest over loan life
Payoff⧉
23.1 years
Your Savings
Interest Saved⧉
$103,448.79
Over the life of the loan
Time Saved⧉
6.9 years
83 months earlier payoff
Planning notes, formulas, and examples
About the Extra Mortgage Payment Calculator
Making extra payments on your mortgage is one of the most straightforward ways to pay off your home faster and save thousands in interest. Whether you add $100 a month, make an annual lump sum, or apply a one-time windfall, every extra dollar applied to principal accelerates your payoff date. The savings are especially dramatic early in the loan, when each payment is overwhelmingly interest and a small extra principal payment prevents years of compounding.
This calculator lets you model three types of extra payments — monthly, annual, and one-time — individually or combined. It re-amortizes your loan with the extra payments and shows you the new payoff date, total interest saved, and how much sooner you will be mortgage-free. You can test different combinations to find the strategy that fits your budget and goals.
Even small extra payments compound over time. An extra $200 per month on a $350,000 loan at 6.5% can save over $70,000 in interest and cut nearly 7 years off a 30-year mortgage.
When This Page Helps
Knowing that extra payments help is intuitive — but quantifying the exact savings is motivating. This calculator turns abstract advice ("pay extra on your mortgage") into concrete numbers: the exact payoff date, total dollars saved, and how each extra payment type contributes to your goal.
Use it to test different scenarios — what if you add $100/month? $500/month? A $10,000 lump sum? — and find the right strategy for your budget.
How to Use the Inputs
- Enter your current loan balance (remaining principal).
- Enter your interest rate and remaining term.
- Enter any extra monthly payment amount (additional principal per month).
- Optionally enter an annual extra payment (e.g., tax refund applied once per year).
- Optionally enter a one-time lump sum payment.
- Review the new payoff date, total interest saved, and years shaved off.
Formula used
Standard amortization: M = P × [r(1+r)^n] / [(1+r)^n − 1]
With extra payments, each period:
Interest = Balance × r
Principal = M − Interest + Extra Monthly + (Extra Annual / 12 amortized)
New Balance = Balance − Principal
The loan is re-amortized by iterating monthly until balance reaches zero. One-time payments reduce the balance immediately in the period they are applied.Example Calculation
Result: Pay off 7.2 years early | Save $89,400 in interest
A $300,000 balance at 6.5% with 28 years remaining has a monthly payment of about $2,028. Adding $200/month extra, $2,000 annually, and a $5,000 one-time payment reduces the term from 28 years to about 20.8 years and saves approximately $89,400 in total interest. The one-time payment alone saves about $12,000; the monthly extra saves about $65,000; the annual payment saves about $12,400.
Tips & Best Practices
- Always specify that extra payments should be applied to principal — some servicers may apply them to the next month's payment instead.
- Start with whatever amount you can afford; even $50/month makes a noticeable difference over 20+ years.
- Use windfalls (tax refunds, bonuses, gifts) as one-time extra payments for an instant savings boost.
- Check for prepayment penalties before making large extra payments — most conventional loans have none, but verify.
- Round up your payment to the nearest $100 for an easy, painless way to pay extra without budgeting stress.
- Combine strategies: a small monthly extra plus an annual lump sum maximizes savings with budget flexibility.
- Refinancing to a lower rate AND making extra payments is the most powerful combination for rapid payoff.
The Power of Compound Savings
Extra mortgage payments work through the same compounding principle that makes mortgages expensive — but in reverse. Every dollar of extra principal today prevents interest from accruing on that dollar for every remaining month of the loan. A $1,000 extra payment in Year 1 of a 30-year loan at 6.5% saves approximately $6,700 in interest over the remaining term.
Three Strategies Combined
The most effective approach combines all three types of extra payments: (1) a consistent monthly extra amount that fits your budget, (2) an annual lump sum from predictable windfalls like tax refunds or bonuses, and (3) occasional one-time payments from unexpected cash. Even if each individual contribution seems small, the three together create a powerful payoff acceleration.
When Not to Pay Extra
Extra mortgage payments are not always the best use of cash. If you have high-interest debt (credit cards, personal loans), pay those first. If you lack an emergency fund (3-6 months of expenses), build that first. And if your mortgage rate is exceptionally low (below 4%), investing the extra cash may yield higher returns. The optimal strategy depends on your complete financial picture.
Sources & Methodology
Last updated:
Methodology
This worksheet starts from the current loan balance, rate, and remaining term, calculates the scheduled principal-and-interest payment, and then re-amortizes the balance after applying the user's extra monthly, annual, and one-time principal payments.
Extra payments are treated as principal-only reductions for planning purposes. Real servicer processing, recast options, and any prepayment restrictions can change the exact payoff date or savings shown.
Sources
- Extra Mortgage Payment Calculator (Fannie Mae) — Consumer guidance on how extra principal payments affect mortgage payoff.
- Understanding amortization (Freddie Mac) — Background on scheduled mortgage amortization and changing principal balance.
- What is a prepayment penalty? (Consumer Financial Protection Bureau) — Why borrowers should check whether extra payoff activity has any contractual limits.
Frequently Asked Questions
On a $300,000 loan at 6.5% for 30 years, an extra $100/month saves approximately $45,000 in interest and cuts about 4 years off the term. The savings increase with higher rates and longer remaining terms.
It depends on your interest rate. If your mortgage rate is above 5-6%, the guaranteed return from prepayment is compelling. Below 4%, investing may yield higher long-term returns. Consider your risk tolerance and the peace of mind that comes with being mortgage-free.
A lump sum applied early in the loan has the greatest impact because it prevents interest from compounding on that principal for the entire remaining term. Monthly extra payments provide steady, disciplined savings. Both are effective — ideally combine them.
Many government-backed and conventional mortgages allow extra principal payments, but borrowers should still confirm the servicer's posting rules and review the note for any unusual restrictions or fees.
When making extra payments online, look for a "principal only" or "additional principal" field. When mailing a check, write "apply to principal" on the memo line and include your loan number. Follow up to confirm it was applied correctly.
No — your required monthly payment stays the same. Extra payments reduce your principal balance, which shortens the loan term and reduces the total interest paid. The payment amount only changes if you formally refinance or recast the loan.
A recast is when your lender re-amortizes your loan after you make a large lump sum payment, resulting in a lower required monthly payment. Unlike refinancing, a recast keeps your current rate and term. Not all lenders offer this option, and there may be a small fee.
As early as possible. In the first years of a mortgage, most of your payment goes to interest. Extra payments early in the loan prevent years of interest accumulation and have the highest compound effect. But starting at any time is still beneficial.
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