How to Read an Amortization Schedule: Where Every Mortgage Payment Actually Goes

The Columns in a Schedule

A standard schedule has six columns: payment number, payment amount, interest portion, principal portion, extra principal (if any), and ending balance. The payment amount is the same every month on a fixed-rate loan. Only the split between interest and principal changes.

To check any row yourself, take the previous ending balance, multiply by the annual rate divided by 12, and you have that month's interest. Subtract it from the payment and the remainder is principal. Subtract principal from the balance and you have the new ending balance. If your lender's schedule disagrees by more than a few cents, ask why, since daily-interest loans and odd first periods can change the first row.

The First Month in Detail

With a $250,000 balance and a monthly rate of 0.065 ÷ 12 = 0.541667%, the first month's interest is $1,354.17. The payment of $1,580.17 leaves only $226.00 for principal, so the balance falls to $249,774.00. More than 85% of the first payment is interest.

In month two, interest is calculated on the smaller balance: $1,352.94. Principal rises to $227.23. The change is tiny, about $1.23 per month, but it compounds. Each month the principal share grows by a little more than the month before, which is why the schedule looks slow at first and then accelerates.

The Crossover Point

In this example, principal first exceeds interest at payment 233, a little past year 19. Before that month, each payment pays down less than half of itself in principal. After it, most of every payment reduces the balance. At a lower rate the crossover comes earlier, and at a higher rate it comes later.

After 5 years (60 payments), you have paid $94,810 in total but the balance has dropped only from $250,000 to $234,027, a reduction of $15,973. That surprises many first-time buyers and explains why selling a home within a few years often yields little equity beyond appreciation and the down payment.

What Year-One Totals Tell You

Over the first 12 payments you pay $18,962 in total, of which $16,168 is interest and only $2,794 is principal. Interest is the true annual cost of borrowing, and some of it may be tax deductible depending on where you live and whether you itemize, so check current rules.

Lenders send an annual statement with the interest paid. You can verify it against the schedule by summing the twelve interest cells.

How Extra Payments Change the Table

An extra payment is applied entirely to principal, so the next month's interest is calculated on a lower balance, and every later row shifts. Adding $200 a month to this loan ends it after roughly 22 years and saves a substantial amount of interest, because you are effectively skipping the high-interest early rows of the schedule.

The cleverest use of a schedule is to look up a future balance. If you want to make a lump-sum payment, find the row for the current month, subtract the lump sum from the balance, and rebuild the remaining rows. Many lenders' online tools do this for you, but doing it once by hand shows why paying early beats paying late.

Adjustable Rates, Biweekly Plans, and Other Variations

On an adjustable-rate mortgage, the schedule is recalculated at each reset using the remaining balance, the new rate, and the remaining term, so the payment column changes. Interest-only periods show zero principal for the first years. Balloon loans show a large final balance. Biweekly plans show 26 half-payments a year. In every case the same rule applies: interest on the opening balance, remainder to principal.