Amortization Schedule
An amortization schedule is a detailed table showing each payment on an installment loan, breaking down how much of each payment goes toward principal (the amount borrowed) versus interest (the cost of borrowing). It tracks the remaining balance after every payment across the entire loan term.
What an Amortization Schedule Shows
When you take out a loan, you don’t just owe back what you borrowed. You owe interest on top of it. The lender needs a way to document exactly how that debt shrinks with each payment. That’s what an amortization schedule does.
Each row in an amortization schedule covers one payment period (typically one month) and displays:
- Payment Number: Which payment in the sequence (1, 2, 3, etc.)
- Payment Amount: The fixed amount you pay (usually the same every month)
- Principal Portion: How much of that payment reduces the balance you owe
- Interest Portion: How much goes to the lender as interest
- Remaining Balance: What you still owe after the payment
The critical insight: early payments are mostly interest. Later payments are mostly principal. The interest shrinks as the balance shrinks.
The Math Behind It
All amortization schedules start with the same core formula for determining the fixed monthly payment:
Where:
- M = Monthly payment
- P = Principal (the original loan amount)
- r = Monthly interest rate (annual rate ÷ 12)
- n = Total number of payments
Once you know the monthly payment, calculating each row is straightforward:
- Interest for that month = Remaining balance × Monthly interest rate
- Principal payment = Total payment − Interest
- New balance = Previous balance − Principal payment
The process repeats for every month until the balance reaches zero.
Sample Amortization Table
Here’s what an amortization schedule looks like for a $200,000 mortgage at 6% annual interest over 30 years (360 payments):
| Month | Payment | Principal | Interest | Balance |
|---|---|---|---|---|
| 1 | $1,199.10 | $199.10 | $1,000.00 | $199,800.90 |
| 2 | $1,199.10 | $200.09 | $999.01 | $199,600.81 |
| 3 | $1,199.10 | $201.09 | $998.01 | $199,399.72 |
| 60 | $1,199.10 | $239.74 | $959.36 | $192,236.48 |
| 180 | $1,199.10 | $457.90 | $741.20 | $100,024.33 |
| 360 | $1,199.10 | $1,195.36 | $3.74 | $0.00 |
Notice how the principal portion starts tiny (Month 1: $199.10) and grows (Month 360: $1,195.36), while interest shrinks from $1,000 to $3.74. The total payment stays constant at $1,199.10.
Mortgage Amortization
Amortization schedules are most common in mortgages. A 30-year fixed mortgage generates a 360-row amortization schedule. After month 120 (10 years), you’ve made $143,892 in payments but only paid down about $40,000 in principal—the rest was interest.
This is why refinancing can save money. If interest rates drop, you might pay less total interest by taking out a new loan at a lower rate, even after paying closing costs. Your new amortization schedule will have a lower interest portion.
See our mortgage guide and mortgage formulas cheat sheet for deeper details.
Amortization vs Depreciation
Don’t confuse amortization with depreciation. They sound similar but mean different things:
- Amortization: Paying down a loan over time by making regular payments
- Depreciation: How an asset loses value over time (accounting term)
You amortize a loan. Assets depreciate. A car loan is amortized; the car itself depreciates.
Extra Payments and Prepayment
If you pay more than the scheduled amount, you reduce principal faster, which shrinks future interest charges. An extra $200 per month on that $200,000 mortgage could cut 5+ years off the loan and save $60,000+ in interest.
Most mortgages allow extra principal payments without penalty. Paying extra early in the loan has the biggest impact because you’re reducing the balance that compounds interest.
Some loans carry prepayment penalties that charge you a fee if you pay off early. Check your loan documents before making extra payments. High-interest debt (like credit card debt) should always be paid off as fast as possible.
Key Takeaways
- An amortization schedule shows the payment, principal, interest, and balance for each period of a loan
- Early payments are mostly interest; later payments are mostly principal
- The monthly payment formula accounts for the principal, interest rate, and loan term
- Amortization applies to mortgages, auto loans, student loans, and most installment debt
- Extra payments reduce principal faster and can save significant interest over time
Frequently Asked Questions
What is the difference between an amortization schedule and a loan statement?
An amortization schedule is a comprehensive breakdown of every payment for the entire loan term. A loan statement is a periodic (usually monthly) summary showing your current balance, recent payments, and upcoming due date. The schedule is a planning tool; the statement is a snapshot.
Can I create my own amortization schedule?
Yes. If you know the loan amount, interest rate, and term, you can calculate the monthly payment using the formula above, then build a spreadsheet that recalculates interest and principal for each row. Most lenders provide amortization schedules automatically, but building one yourself helps you understand exactly how loans work.
Why is most of my first payment interest?
Interest is calculated on the current balance. In month one, you owe the full principal amount, so the interest charge is highest. As you pay down the balance, the interest charge shrinks. This is why early prepayment is so powerful—reducing the balance now saves interest on every future payment.
Does amortization apply to auto loans?
Yes. Auto loans, personal loans, and most installment loans use amortization. Each has its own schedule. A 5-year auto loan has 60 rows; a 10-year personal loan has 120 rows. The math is identical, just with different numbers.
How does compound interest relate to amortization?
Amortization prevents simple interest from snowballing. By making regular payments, you’re stopping the balance from growing. Without amortization (and without making payments), your loan balance would compound and grow exponentially, which is why defaulting is so costly.