Reading the schedule
Each row is one payment. The payment amount stays the same throughout, but its composition shifts steadily: early payments are mostly interest, late payments are mostly principal. That is not a fee structure or a trick, it is arithmetic — interest is charged on what you still owe, and early on you still owe nearly everything.
The consequence catches people out when they sell or refinance a few years in and discover how little the balance has moved. On a 30-year mortgage at 6.5%, more than half of every payment is still interest until well past the seventeen-year mark. The tool names that crossover month directly, because it is the single most useful number in the table and no schedule usually points it out.
Why the total may differ slightly from other calculators
Interest here is computed the way a servicer computes it: the remaining balance multiplied by the monthly rate, rounded to whole cents, every month, with the final payment trimmed to clear the balance exactly rather than overshooting.
Formula-based calculators instead multiply the payment by the number of payments and subtract the principal. Across a 30-year loan the two approaches differ by a few dollars — under a cent per payment — because rounding accumulates. Neither is wrong, but the schedule is the one that will match your statements, which is why this page uses it.
What the schedule cannot tell you
It assumes a fixed rate, payments arriving exactly on schedule, and nothing extra ever paid. Adjustable-rate loans re-amortize whenever the rate resets. Escrow for property tax and insurance is collected alongside the payment on most mortgages but is not part of the loan, so your actual monthly bill is higher than the figure here — the mortgage calculator includes those.
If you are planning to pay more than the required amount, the schedule above will not reflect it. The extra payment calculator reruns the whole loan with the additional money applied and reports what it removes in months and interest.
Frequently asked questions
Why is so much of my early payment interest?
Interest is charged on the balance outstanding, and early in a loan you still owe almost all of it. The payment stays constant while its split shifts, so the interest share falls only as the balance does.
When does more of my payment go to principal than interest?
The tool names that month directly for your figures. On a 30-year loan at 6.5% it arrives well past the seventeen-year mark, which is much later than most people assume.
Why does the total interest differ slightly from other calculators?
This schedule rounds each month\u2019s interest to cents and trims the final payment, exactly as a servicer does. Formula-based calculators multiply payment by term instead. Over 30 years the two differ by a few dollars.