10-Year Fixed Loan Calculator: Payoff Calendar

What a payoff calendar adds to a payment quote

A payment quote answers one question: how much is due each month. A payoff calendar answers the ones that come next. It shows the month of the first payment, the month of the last one, how many payments sit between them, and how much of each payment is interest.

For a 10-year fixed loan the count is fixed at 120 monthly payments. If the first payment is November 2026, payment 120 lands in October 2036, because 119 months separate the first payment from the last. The calculator uses the month you enter as the first payment month, not the month the money was funded.

That distinction matters at signing. A lender may disburse in November and set the first payment in January, which pushes the payoff two months later without changing the payment. The CFPB's explanation of how paying down a mortgage works (last reviewed 2024) describes the same split between interest and principal, and the calendar is where that split becomes visible month by month.

The payment on $25,000 at 7.50%

Use the standard amortization formula: P = L x r x (1 + r)^n / ((1 + r)^n - 1), with L = 25,000, r = 0.075 / 12 = 0.00625 and n = 120. The factor (1 + r)^n comes to 2.1121, so the payment is 25,000 x 0.00625 x 2.1121 / 1.1121 = 296.7544, or $296.75.

The unrounded math gives $35,610.53 in total payments and $10,610.53 in interest. Rounding the payment down to $296.75 and each month's interest to the cent moves the total to $35,610.79, and the final payment to $297.54. Interest is 29.8% of everything paid.

That 26 cent gap is not an error. It is the cost of keeping a ledger in whole cents, and a servicer's statement will show the same kind of drift. The calculator reproduces the cent-level schedule, so its total interest matches a lender's statement rather than the clean textbook figure.

Where the money goes, year by year

In the first month the balance is $25,000, so interest is 25,000 x 0.00625 = $156.25 and principal is $140.50. By the last month interest is $1.85 and principal is $295.69. The payment stays level while the mix flips.

Across the first year, $1,815.82 goes to interest and $1,745.18 to principal, so interest is 51.0% of the 12 payments. By year five the split is $1,207.46 interest and $2,353.54 principal. In year ten it is $140.60 interest and $3,421.19 principal.

The balance falls slowly at first and then quickly. After three years $19,347.48 is still owed, 77.4% of the original loan. After eight years the balance is $6,595.19. A payoff calendar makes those turning points visible; a monthly payment quote hides them behind one number.

Biweekly payments: 26 half payments a year

Biweekly means paying half the monthly payment every two weeks. Half of $296.75 is $148.38, and 26 payments a year come to $3,857.88. Twelve monthly payments come to $3,561.00, so the biweekly schedule sends an extra $296.88 to the lender each year, roughly one more monthly payment.

That extra payment is the whole trick. It is not a different interest rate, and it does not require a new loan. The balance drops faster, so less interest accrues, and the loan ends sooner. On this loan the biweekly schedule takes 232 half payments, or just under 9 years, and costs $9,285.16 in interest. The monthly schedule costs $10,610.79, so the saving is $1,325.63.

The schedule assumes the lender applies each half payment when it arrives. Some servicers hold half payments until a full payment is due, which removes most of the benefit, and some biweekly programs charge a setup fee. Ask how the money is applied before enrolling, and compare the fee with the $1,325.63 saving.

The payoff month in biweekly mode

The first and last of the 232 half payments sit 3,234 days apart, about 8.9 years. Starting with a first payment in November 2026, the last one lands in September 2035. The monthly schedule ends in October 2036, so the calendar moves up by 13 months.

The order of the dates is fixed for a given balance and rate: November 2026, September 2035, October 2036. Changing the start month shifts all three by the same amount. Changing the rate changes the gap, because a higher payment makes the extra annual payment worth more.

Interest compounding differs a little between the two modes. The monthly schedule compounds at 7.50% / 12 and produces an effective annual rate of 7.76%. The biweekly schedule compounds at 7.50% / 26, an effective 7.78%. The simulation uses those period rates, so the comparison does not quietly assume that 26 half payments equal 13 monthly payments to the day.

Rate sensitivity: what half a point does

On a $25,000 balance with 10 years left, each half point of rate moves the payment by about $6.50 and the total interest by $770 to $800. The table below runs the same 120 payments at 6.50%, 7.00%, 7.50%, 8.00% and 8.50%.

At 6.50% the payment is $283.87 and interest is $9,064.38. At 8.50% the payment is $309.96 and interest is $12,196.01. The gap between those two rates is $26.09 a month and $3,131.63 over the term. A full point at the middle of the range is worth $1,546.41 (7.50% down to 6.50%) or $1,585.22 (7.50% up to 8.50%).

The payment moves in a straight line for practical purposes, but the interest total does not: the same half point costs more at a higher rate. That is why a quote at 8.00% versus 7.50% should be read in dollars over 120 months, not in the monthly difference alone. A $6.57 monthly gap sounds small until it is multiplied by 120.

Why the last payment rarely matches the rest

Lenders quote a payment rounded to the cent, but the formula almost never lands on a whole cent. The difference has to go somewhere, and it goes into the final payment. If the quoted payment is rounded up, the last payment is a little smaller. If it is rounded down, the last payment is a little larger.

On this loan the exact payment is $296.7544. Rounding down to $296.75 leaves $297.54 for the last payment. A servicer that rounds the other way, or that accrues interest on the actual days between payments, will show a slightly different final figure and a total that differs by a few cents.

The first payment can also differ. When a loan funds in the middle of a month, the first payment may include interest for the days before the first full month, which is why the first statement sometimes shows a number that matches neither the quote nor the schedule. The calculator assumes a clean first-of-month schedule and says so.

Checking a servicer's schedule against your own math

Open the schedule and check four columns: opening balance, interest, principal and closing balance. Interest should equal the opening balance times the annual rate divided by 12. Principal should equal the payment minus that interest. The closing balance should equal the opening balance minus principal. If any row breaks one of those rules, the row is wrong.

Run the same check at the end. A 10-year loan should have 120 rows, a closing balance of zero, and total interest that matches the sum of the interest column. On this loan the totals are $10,610.79 in interest, $35,610.79 paid, and a final payment of $297.54.

Two conventions can make a correct schedule look wrong. Some lenders accrue interest on actual days, so a payment made a few days late changes the split. Others apply payments in a different order when fees are owed. The CFPB's amortization explainer (2024) covers the standard pattern, and FRED's 10-year Treasury series (2026) is a place to see how benchmark rates moved while you shopped.