Amortization Calculator (Loan Schedule)
Full amortization schedule for any fixed-rate loan. See monthly P+I, total interest, payoff time, and savings from extra payments.
FINANCEThis amortization calculator turns any fixed-rate loan - mortgage, auto, or student - into a month-by-month payment plan. It shows your monthly principal-plus-interest payment, the lifetime interest cost, and a year-by-year breakdown of how the balance falls. Add an optional extra monthly payment to see how much faster you pay off and how much interest you save.
The math behind every amortization schedule is M = P × r(1+r)^n / ((1+r)^n - 1), where P is the loan amount, r is the monthly rate (APR ÷ 12), and n is total months. Example: a $400,000 mortgage at 7% APR over 30 years gives r = 0.005833 and n = 360, producing M ≈ $2,661.21. Over the full term you pay back about $958,000 - meaning $558,000 of interest on the original $400k. Add $200 extra principal per month and the loan ends in roughly 24 years, saving close to $100,000 in interest.
Amortization Calculator (Loan Schedule)
Build a full amortization schedule for any fixed-rate loan - mortgage, auto, or student. See how each payment splits between interest and principal, and how extra payments shorten the term.
Year-by-Year Schedule
| Year | Principal | Interest | End Balance |
|---|---|---|---|
| 1 | $4,063 | $27,871 | $395,937 |
| 2 | $4,357 | $27,578 | $391,580 |
| 3 | $4,672 | $27,263 | $386,908 |
| 4 | $5,010 | $26,925 | $381,898 |
| 5 | $5,372 | $26,563 | $376,526 |
| 6 | $5,760 | $26,174 | $370,766 |
| 7 | $6,177 | $25,758 | $364,590 |
| 8 | $6,623 | $25,311 | $357,967 |
| 9 | $7,102 | $24,833 | $350,865 |
| 10 | $7,615 | $24,319 | $343,250 |
How Amortization Works
Amortization spreads a fixed-rate loan into equal monthly payments using M = P × r(1+r)^n / ((1+r)^n - 1), where P is principal, r is the monthly rate (APR ÷ 12), and n is total months. On a $400,000 mortgage at 7% for 30 years, M ≈ $2,661. Each month, interest = remaining balance × r, principal = M - interest, and the balance drops by that principal amount. The math guarantees the loan reaches zero exactly at month n.
Early payments are mostly interest because the balance is highest at the start. On that $400k loan, month 1 sends about $2,333 to interest and only $328 to principal. By year 15 the split flips and most of each payment finally chips at principal. This back-loaded equity buildup is why selling a home in the first 5-7 years often returns very little appreciation after closing costs - you barely paid down the loan.
Extra principal payments shorten the term dramatically because they kill future interest. Adding just $200/month to a 7% 30-yr $400k mortgage pays it off in roughly 24 years and saves about $100k in interest. The biweekly trick (half payment every 2 weeks = 13 full payments per year) gives a similar effect. Compare against investing instead: if you can earn more after-tax than your loan rate, invest. Mortgage interest is deductible only on loans up to $750k under TCJA, which lowers the effective rate further.
Educational tool only. Real loans may include escrow, PMI, or origination fees not modeled here. Contact your lender for an exact payoff quote and official amortization schedule.