If you’ve ever looked at your mortgage statement and wondered why so little of your payment goes to the actual loan balance — you’re experiencing amortization. Understanding how it works can save you thousands.
What Is Loan Amortization?
Amortization is the process of spreading loan payments over time so that each payment covers both interest and principal. Early in a loan, most of your payment goes to interest. Over time, the balance shifts until your final payment is almost entirely principal.
The Monthly Payment Formula
M = P × [r(1+r)^n] ÷ [(1+r)^n − 1]
- M = Monthly payment | P = Loan amount | r = Monthly interest rate | n = Total payments
Example Amortization Schedule
$300,000 mortgage at 6.5% for 30 years. Monthly payment: $1,896
| Month | Payment | Interest | Principal | Balance |
|---|---|---|---|---|
| 1 | $1,896 | $1,625 | $271 | $299,729 |
| 12 | $1,896 | $1,609 | $287 | $296,761 |
| 60 | $1,896 | $1,533 | $363 | $280,993 |
| 180 | $1,896 | $1,207 | $689 | $221,048 |
| 300 | $1,896 | $509 | $1,387 | $92,571 |
| 360 | $1,896 | $10 | $1,886 | $0 |
Total paid: $682,560 | Total interest: $382,560
How to Pay Off Your Loan Faster
- Make extra principal payments — Even $100 extra/month on a $300k mortgage at 6.5% saves ~$65,000 in interest and 5+ years.
- Bi-weekly payments — Pay half your monthly payment every two weeks. This results in 26 half-payments (13 full payments) per year, cutting years off the loan.
- Refinance to a shorter term — 15-year mortgages have higher payments but dramatically lower total interest.
- Lump-sum payments — Apply tax refunds, bonuses, or inheritance directly to principal.
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