What is an Amortization Schedule?
An amortization schedule is a complete table of loan payments, sorted by date. Each row represents one payment and shows: the total payment amount, how much of that payment goes toward interest, how much reduces your principal, and the remaining balance after the payment.
The key insight: even though your monthly payment stays constant (for fixed-rate loans), the split between interest and principal changes dramatically over time.
The Monthly Payment Formula
Where M = monthly payment, P = loan principal, r = monthly interest rate (annual rate ÷ 12), n = total number of monthly payments.
Why Early Payments Are Mostly Interest
For a $200,000 mortgage at 6% for 30 years (360 payments), the monthly payment is $1,199.10. In the very first payment:
- Interest portion: $200,000 × (0.06 ÷ 12) = $1,000
- Principal portion: $1,199.10 − $1,000 = $199.10
Only $199 of your first $1,199 payment reduces what you owe! After 5 years of payments, you've paid approximately $71,946 but trimmed only $13,630 off the principal. The bank collected $58,316 in interest.
This reverses over time. By payment 301 (year 25), the interest portion drops to roughly $400 and the principal portion climbs above $800.
How to Use an Amortization Schedule Strategically
1. Make Extra Principal Payments
Even a single extra payment applied directly to principal each year can shorten a 30-year mortgage by 4–5 years. Use our loan calculator to model this scenario — enter a higher monthly payment and watch the schedule compress.
2. Refinancing Resets the Clock
Refinancing a loan to a lower rate sounds appealing, but it restarts amortization from year 1. If you're in year 20 of a 30-year mortgage and switch to a new 30-year loan at a lower rate, you extend your debt by 20 years. Always compare total interest paid over the full life of both loans, not just the monthly payment.
3. The Break-Even Point of Refinancing
Refinancing has closing costs (typically 2–5% of the loan amount). To find your break-even point: divide your closing costs by your monthly savings. If closing costs are $4,000 and you save $150/month, your break-even is 26.7 months. Only refinance if you plan to stay in the home longer than that.
Sample Amortization Table (First 5 Rows)
| Month | Payment | Interest | Principal | Balance |
|---|---|---|---|---|
| 1 | $1,199.10 | $1,000.00 | $199.10 | $199,800.90 |
| 2 | $1,199.10 | $999.00 | $200.10 | $199,600.80 |
| 3 | $1,199.10 | $998.00 | $201.10 | $199,399.70 |
| 4 | $1,199.10 | $997.00 | $202.10 | $199,197.60 |
| 5 | $1,199.10 | $996.00 | $203.10 | $198,994.50 |
Notice how the interest portion decreases by just $1 each month in the early years — highlighting just how slow principal paydown actually is at the beginning of a long-term loan.