How Loan Amortization Works (With an Example Schedule)
By Arshi Khan, Founder of Just4Marketing · October 26, 2026 · 6 min read
Why your fixed loan payment is mostly interest at first, a month-by-month example schedule, and what amortization means for extra payments and refinancing.
Your loan payment stays the same every month, but what it pays for doesn't. Early on, most of it goes to interest; by the end, almost all of it goes to the balance. That shifting split is called amortization, and understanding it explains why extra payments are so powerful and why a 30-year mortgage barely moves in its first few years.
How each payment is split
Every month, the lender does three things:
- works out the interest: the balance × the annual rate ÷ 12,
- takes that interest out of your payment, and
- uses whatever is left to reduce the balance.
Because the balance falls a little each month, next month's interest is a little lower, and a little more of the same payment goes to principal. Repeat that for every month of the loan and the balance reaches exactly zero on the final payment.
An example schedule
A $25,000 loan at 8.5% over 5 years has a fixed payment of $512.91. Here are the first and last months:
| Month | Interest | Principal | Balance left |
|---|---|---|---|
| 1 | $177.08 | $335.83 | $24,664.17 |
| 2 | $174.70 | $338.21 | $24,325.96 |
| 3 | $172.31 | $340.60 | $23,985.36 |
| … | … | … | … |
| 59 | $7.19 | $505.72 | $509.31 |
| 60 | $3.61 | $509.31 | $0.00 |
Month 1 interest is $25,000 × 8.5% ÷ 12 = $177.08. By the last month, only $3.61 of the payment is interest. Over the whole loan you pay $5,774.80 in interest.
Why a mortgage feels slow at first
The longer the loan, the more extreme the early split. On a $300,000 mortgage at 6.5% over 30 years, the payment is $1,896.20. In the first year you pay about $22,750 — but only about $3,350 of that reduces the balance. The rest, about $19,400, is interest.
| After | Balance left | Paid off so far |
|---|---|---|
| 5 years | About $280,800 | 6% |
| 10 years | About $254,300 | 15% |
| 15 years | About $217,700 | 27% |
| 20 years | About $167,000 | 44% |
| 30 years | $0 | 100% |
Halfway through the term, you've paid off barely a quarter of the loan. Principal doesn't overtake interest in each payment until month 233 — more than 19 years in.
What this means for you
- Extra payments early save the most. Money paid toward principal in year one skips decades of interest.
- Refinancing into a new 30-year loan restarts the slow phase, which is why a lower rate doesn't always save money overall.
- Equity builds slowly at first. If you sell after a few years, most of what you paid went to interest, and selling costs can exceed the equity you've built.
- Shorter terms change the split. On a 15-year loan at 5.75%, about 42% of the first payment goes to principal, against 14% on the 30-year loan above.