Amortization Schedule Calculator
See how your loan balance falls year by year, how much of each year's payment goes to principal vs. interest, and how an extra monthly principal payment shortens the loan. The schedule below uses the same engine TrueOwn runs on real mortgages.
The starting balance — what you borrowed.
Annual rate.
Optional. Goes straight toward what you owe, on top of the regular payment.
Term resets the schedule. Most U.S. mortgages are 30-year fixed.
Base 30-year schedule at 6.50%
$2,023 / month
- Principal
- $320,000
- Interest
- $408,141
- Loan Amount
- $320,000
- Total Interest
- $408,141
- Payoff Year
- 2056
Free during pilot
How amortization works
On a fixed-rate mortgage, every monthly payment is the same dollar amount — but the split between principal and interest changes month-over-month. Each month, interest accrues on the remaining balance at r ÷ 12, and whatever's left of the payment goes to principal.
Early in the loan, most of the payment is interest. As the balance falls, the interest portion shrinks and the principal portion grows. That's why an extra principal payment in year 1 has a much larger cumulative effect than the same payment in year 25.
Extra-principal acceleration
Adding an extra principal payment each month leaves the regular payment unchanged but shrinks the balance faster. The acceleration compounds: a smaller balance means less interest accrues next month, which means more of the next regular payment goes to principal.
The schedule shown stops as soon as the accelerated balance reaches zero — that's the "months saved" you see in the result. Note: most servicers require you to explicitly designate extra funds as "principal only," otherwise they may apply the surplus to your next regular payment instead.
What this calculator deliberately excludes
- Property taxes, insurance, PMI. Not part of P&I (principal and interest). Use the mortgage payment calculator for the same picture without the schedule, or link your mortgage for the full PITI (principal, interest, taxes, and insurance).
- ARMs and graduated-payment loans. The schedule assumes a fixed rate for the entire term.
Frequently asked questions
What is an amortization schedule?
An amortization schedule is the period-by-period breakdown of how each fixed mortgage payment splits between interest and principal, and how the balance falls over the loan term. On a fixed-rate loan the payment amount stays constant — only the split between interest and principal changes.
Why does the principal and interest split change every month?
Interest accrues on the remaining balance each month at the annual rate ÷ 12. Because the balance is highest at the start, the interest portion is largest early in the loan and shrinks over time, so a growing share of each payment goes to principal.
How much does paying extra principal save?
Extra principal each month leaves your regular payment unchanged but retires the balance faster, and the effect compounds: a smaller balance accrues less interest, so more of the next payment goes to principal. Enter an extra-monthly amount above to see the interest saved and how many months earlier the loan pays off.
Do I need to tell my servicer the extra payment is for principal?
Usually yes. Most servicers require you to explicitly designate extra funds as 'principal only,' otherwise they may apply the surplus toward your next scheduled payment instead of reducing the balance. Check your servicer's prepayment instructions.
Does this schedule work for adjustable-rate mortgages?
No. The schedule assumes a fixed rate for the entire term, no missed payments, and extra principal applied on the same day each month. ARMs and graduated-payment loans recalculate when the rate changes, so the projection would diverge after the first adjustment.
Estimates only — not a lending decision. The schedule assumes a fixed rate, no missed payments, and that extra principal is applied on the same day each month. Your servicer's rounding, prepayment rules, and escrow analysis may produce slightly different month-by-month numbers. Methodology last reviewed: May 26, 2026.