Mortgage Payoff Calculator

Most homeowners pay their mortgage exactly as scheduled for decades. Yet a fixed-rate loan can almost always be paid off faster, and doing so can cut tens of thousands of dollars from the interest bill. The two calculators above model the common strategies: a bit extra each month, a lump sum once a year, a single one-time payment, half-payments every two weeks, or clearing the whole balance at once.

Both calculators assume principal-and-interest only. Property tax, insurance and PMI held in escrow are separate charges that do not affect how quickly the loan balance falls, so leave them out of the payment you enter. Results are estimates; your servicer's payoff quote, which includes interest accrued to the exact payoff date, is the final word.

Principal and Interest of a Mortgage

Each monthly payment on an amortizing mortgage has two parts. Interest is the lender's charge for the month, worked out by multiplying the outstanding balance by the monthly rate. Principal is everything left over, and it is the only part that actually reduces what you owe.

Because interest depends on the current balance, the mix changes over time. On a new 30-year loan at 6%, roughly 83% of the first payment is interest. Halfway through, the split is closer to even, and in the last few years nearly the entire payment is principal. That front-loading is why paying extra early in the loan has such a large effect: principal removed in year two would otherwise have accrued interest for another 28 years.

The balance falls according to a simple monthly rule, shown below. The calculator applies it month by month, adding any extra payments you specify, until the balance reaches zero.

Interest this month = balance × r · New balance = balance + interest − (payment + extra)

r

monthly interest rate (annual rate ÷ 12)

payment

scheduled principal-and-interest payment

extra

any additional principal paid that month

Because interest is charged only on the balance still owed, every extra dollar of principal removes all the future interest that dollar would have generated.

Extra Payments

Paying more than the required amount is the most flexible way to shorten a mortgage. Most servicers let you add extra principal to any monthly payment, mark a separate payment as principal-only, or send a lump sum at any time. A raise, bonus or tax refund can be directed to the loan without committing to a higher payment forever.

When you pay extra, check your statement to make sure the money went to principal and not to next month's payment. Extra payments do not usually lower your required monthly payment; they shorten the loan instead, unless you ask the lender to recast it.

Biweekly Payments

With a biweekly plan you pay half your monthly payment every two weeks. A year has 52 weeks, so you make 26 half-payments, the equivalent of 13 monthly payments instead of 12. That one extra payment a year, applied straight to principal, typically trims four to six years off a 30-year loan.

Some companies charge setup or per-payment fees for biweekly programs. You can get almost the same result for free by adding one-twelfth of a monthly payment to each regular payment.

Refinance to a shorter term

Refinancing replaces your current loan with a new one, and moving from a 30-year to a 15-year term is a structured way to pay off sooner. Shorter loans usually carry lower rates, so the savings come from both a smaller rate and fewer years of interest. The trade-off is a higher required payment, which removes the flexibility you keep when you simply prepay a longer loan.

A refinance also comes with closing costs, often 2% to 5% of the loan, plus appraisal and title fees. It makes the most sense when the new rate is meaningfully lower than the old one and you expect to stay in the home long enough for the interest savings to exceed those costs. Compare scenarios with the refinance calculator before applying.

Prepayment Penalties

A prepayment penalty is a fee some lenders charge when a loan is paid off, or substantially paid down, early. It compensates the lender for interest it expected to earn. Penalties are often a percentage of the outstanding balance or a set number of months of interest, and they usually apply only during the first few years.

Federal rules adopted after the 2008 crisis sharply limit these fees. For most qualified mortgages made since 2014, a penalty is allowed only on certain fixed-rate loans, only during the first three years, and capped at 2% of the balance in years one and two and 1% in year three. Adjustable-rate and higher-priced loans cannot carry one at all.

Even when a penalty exists, it often applies only to a full payoff or a refinance, not to modest extra payments. Look for a prepayment clause in your promissory note or closing disclosure, or ask your servicer directly before you start paying ahead.

Opportunity Costs

Money sent to the mortgage is money that cannot be used for anything else, so it is worth asking what else it could do. Paying ahead earns a guaranteed return equal to your mortgage rate, risk-free. Whether that is a good deal depends on the alternatives.

Retirement savings come first for many people, especially when an employer matches contributions; a match is an instant return that no mortgage can beat. Tax-advantaged accounts such as a 401(k) or IRA also compound for decades. Over long periods a diversified stock portfolio has historically returned more than typical mortgage rates, though with real ups and downs along the way.

Liquidity matters too. Home equity is hard to reach quickly: to get it back you have to sell, refinance or borrow against the house, and lenders tighten credit exactly when times are hard. An emergency fund of three to six months of expenses should be in place before you prepay. High-interest debt such as credit cards and private loans should be cleared first, because those rates are usually far above any mortgage rate.

Taxes can shift the comparison slightly. If you itemize deductions, part of your mortgage interest is deductible, which lowers your effective rate a little. Since the standard deduction roughly doubled in 2018, most households no longer itemize, so for them the full mortgage rate is the right yardstick.

Finally, consider the non-financial side. Owning your home outright lowers your fixed costs in retirement and many people value that peace of mind above a slightly higher expected return elsewhere.

Examples

Take a $400,000, 30-year mortgage at 6%. The principal-and-interest payment is $2,398.20, and over the full term the borrower would pay $463,352.76 in interest. After five years of regular payments, 25 years remain and the balance is $372,217.43.

Extra $500 a month from that point: the loan is paid off in 17 years and 3 months instead of 25 years, and the remaining interest falls from $347,243.20 to $224,937.00. That is $122,306 less interest, about 26% of the original total, and the mortgage ends 7 years and 9 months early.

Biweekly payments instead: paying $1,199.10 every two weeks makes the equivalent of one extra monthly payment a year. On the same $372,217.43 balance, the loan ends in about 21 years rather than 25 and the remaining interest drops by roughly $64,000.

One-time lump sum: if the borrower receives a $50,000 inheritance and applies it all to principal now while keeping the regular payment, the remaining term shrinks from 25 years to 18 years and 8 months. A lump sum has the largest effect when made early, because it removes the most months of interest.

Unknown remaining term: someone who owes $230,000 and pays $1,500 a month at 6% has 24 years and 4 months left and will pay $207,677.36 in interest. Adding $500 a month cuts that to 14 years and 4 months and $113,122.63 of interest, saving $94,555, or about 46% of the remaining interest, and finishing ten years sooner.

These examples show the general pattern: modest, consistent extra payments early in a loan produce outsized savings, and the effect shrinks the closer you are to the end of the term.

Frequently asked questions

Sources

• CFPB – Prepayment penalties
• Consumer Financial Protection Bureau – Owning a Home