What amortization means
Amortization is the process of paying off a loan with equal payments over time. Each payment covers the interest due that month plus a portion of the principal. Early on, most of your payment is interest; as the balance shrinks, more goes to principal — which is why payoff accelerates near the end.
The payment itself never changes: payment = loan × r ÷ (1 − (1 + r)−n), where r is the monthly rate (annual rate divided by 12) and n is the total number of payments. Only the split inside that payment moves. A full amortization schedule lists, month by month, the interest charged, the principal repaid and the balance remaining, which is how you can tell exactly what you would still owe if you sold or refinanced in year seven. The same schedule sits behind the monthly payment figure produced by the loan calculator.
Worked example
On a $250,000 loan at 6% over 30 years, the payment is about $1,499/month. In month one, roughly $1,250 of that is interest and only ~$249 reduces the balance. Over 30 years you'd pay about $290,000 in interest — more than the loan itself.
The crossover point, where principal finally exceeds interest within a single payment, arrives close to year eighteen on that loan. Choosing a shorter term moves it much earlier and changes the total dramatically: the same borrowing at the same rate over 15 years costs more each month, but the interest bill falls by roughly half because the balance is retired far faster. For a house, run the same inputs through the mortgage calculator, which also folds in taxes and insurance.
How extra payments help
Because interest is charged on the remaining balance, any extra principal you pay early removes interest from every future month. Even small recurring overpayments can cut years off the term and save tens of thousands in interest.
Ask your lender to apply overpayments to principal rather than treating them as a prepaid future instalment, and check whether your loan carries a prepayment penalty before you start. Every schedule shown here assumes a fixed rate, on-time payments and no fees, so treat the output as an estimate for general information rather than financial advice. Revolving balances amortize differently, so use the credit card payoff calculator for those.
Frequently asked questions
- Why is so much early payment interest?
- Interest is charged on the outstanding balance, which is highest at the start. As the balance falls, the interest portion of each payment shrinks.
- Does this apply to any loan?
- Yes — mortgages, auto loans and most personal loans amortize the same way with equal fixed payments.
- Does one extra payment a year really help?
- Yes, and by more than most people expect. An extra monthly payment each year goes entirely to principal and typically cuts several years off a 30-year loan, because it removes all the future interest that principal would have generated.
- Does the monthly payment include taxes and insurance?
- No. This tool shows principal and interest only. Property taxes, homeowners insurance and any mortgage insurance are collected separately by your lender, usually through an escrow account added on top of this figure.
- How accurate is the schedule shown here?
- It is an estimate for general information, not financial advice. Lenders round payments differently and may add origination or servicing fees, so your real schedule can differ by a few dollars a month.