On a $400,000 mortgage at 6.50% over 30 years, your monthly principal-and-interest payment is $2,528, and in the very first month $2,167 of it is interest while only $362 reduces what you owe. That split is what a mortgage amortization schedule shows: every payment, divided between interest and principal, with the remaining balance after each one. Over the full term, the interest alone comes to $510,178.
To see the schedule for your own loan, enter your numbers in our mortgage calculator. The rest of this guide shows how the schedule is built, so you can check any lender's version yourself.
Key Takeaways
- Rule of thumb: in year 1 of this loan, $25,868 of the $30,339 paid (85.3%) is interest.
- The payment on a fixed-rate loan never changes, but the interest-to-principal split flips over time.
- On the example loan, principal first exceeds interest in month 233, 19 years and 5 months in.
- You pass the halfway point of the balance in month 257 (21 years and 5 months), not at year 15.
- An extra $200 a month cuts the term to 24 years and 5 months and saves $111,892 in interest.
What Is a Mortgage Amortization Schedule?
An amortization schedule is a table with one row per payment. Each row lists the payment amount, how much of it covers interest, how much reduces principal, and the balance left afterward. "Amortize" just means to pay a debt down in scheduled installments, so that the balance reaches exactly zero on the final payment.
Your lender or loan servicer can provide the schedule for your loan, and many include one in the closing paperwork. But you do not need to wait for it. Every number in it follows from three inputs: the loan amount, the interest rate, and the term.
How the Schedule Is Calculated
Two formulas do all the work. First, the fixed monthly payment:
PMT = P × r × (1 + r)n / ((1 + r)n − 1)
Here P is the loan amount, r is the monthly rate (annual rate divided by 12), and n is the number of monthly payments. For $400,000 at 6.50% over 360 months, r is 0.0054167 and the payment is $2,528.
Second, each month's split. Interest is the current balance times the monthly rate. Whatever is left of the payment goes to principal:
- Month 1 interest: $400,000 × 0.0054167 = $2,166.67
- Month 1 principal: $2,528.27 − $2,166.67 = $361.61
- New balance: $400,000 − $361.61 = $399,638.39
- Month 2 interest: $399,638.39 × 0.0054167 = $2,164.71, so principal rises slightly to $363.56
Repeat that 360 times and you have the whole schedule. Because interest is charged on a shrinking balance, the interest portion falls a little each month and the principal portion rises by the same amount.
The Schedule in Numbers: $400,000 at 6.50%
Here are selected months from the full schedule (principal and interest only, no taxes or insurance):
| Payment # | Interest | Principal | Remaining balance |
|---|---|---|---|
| 1 | $2,166.67 | $361.61 | $399,638.39 |
| 2 | $2,164.71 | $363.56 | $399,274.83 |
| 12 | $2,144.53 | $383.74 | $395,529.10 |
| 60 | $2,030.93 | $497.34 | $374,443.91 |
| 120 | $1,840.54 | $687.73 | $339,104.51 |
| 180 | $1,577.27 | $951.01 | $290,236.56 |
| 240 | $1,213.20 | $1,315.07 | $222,661.13 |
| 300 | $709.77 | $1,818.50 | $129,216.65 |
| 360 | $13.62 | $2,514.65 | $0.00 |
And the same loan summarized by year:
| Loan year | Interest paid | Principal paid | Balance at year end |
|---|---|---|---|
| 1 | $25,868 | $4,471 | $395,529 |
| 2 | $25,569 | $4,770 | $390,759 |
| 5 | $24,545 | $5,794 | $374,444 |
| 10 | $22,327 | $8,013 | $339,105 |
| 15 | $19,259 | $11,080 | $290,237 |
| 20 | $15,018 | $15,322 | $222,661 |
| 25 | $9,152 | $21,187 | $129,217 |
| 30 | $1,042 | $29,298 | $0 |
The table makes a point the monthly payment hides. After five years of on-time payments, you have paid $151,696 in total but your balance has fallen only from $400,000 to $374,444, a drop of $25,556. The rest went to interest.
Why the First Years Feel Slow
Interest is calculated on the balance, and the balance is largest at the start. That is the whole mechanism. There is no hidden fee or front-loading trick, just arithmetic on a big number.
Two milestones are worth knowing. Principal overtakes interest in payment 233, which is about 19 years and 5 months in. And the balance drops below $200,000 only in payment 257. So the "halfway" point of a 30-year loan, measured in dollars owed, arrives in year 21 and 5 months, not year 15.
That is also why selling or refinancing in the first several years builds little equity from paydown alone. In the early years, your down payment and any change in the home's value matter more to your equity than paydown does. If you are weighing a refinance, our guide to mortgage refinancing covers how a reset restarts this front-loaded interest curve.
How Rate Changes the Schedule
The same $400,000, 30-year loan at three different rates (principal and interest only):
| Rate | Monthly payment | Total interest over 30 years |
|---|---|---|
| 6.00% | $2,398 | $463,353 |
| 6.50% | $2,528 | $510,178 |
| 7.00% | $2,661 | $558,036 |
Moving from 6.00% to 6.50% adds $130 to the monthly payment and $46,825 to total interest. Moving from 6.50% to 7.00% adds another $133 a month and $47,858 in interest. These three rates are illustrations that bracket a plausible range, not a market quote. Use the rate printed on your own Loan Estimate when you build your schedule.
What Extra Payments Do to the Schedule
Any extra money sent toward principal reduces the balance immediately. Next month's interest is then charged on a smaller number, so every later row of the schedule changes. Here is the effect of a fixed extra amount added to every payment on the example loan:
| Extra per month | Payoff time | Total interest | Interest saved |
|---|---|---|---|
| None | 30 years | $510,178 | — |
| +$100/month | 26 years 10 months | $446,261 | $63,917 |
| +$200/month | 24 years 5 months | $398,286 | $111,892 |
| +$500/month | 19 years 5 months | $304,621 | $205,557 |
Two cautions. First, tell your servicer the extra is for principal, so it is not treated as an early payment of next month's installment. Second, check your loan documents for a prepayment penalty and ask your servicer how extra principal payments are applied. For a comparison of paying early versus investing the difference, see paying off your mortgage early vs investing. If a payment schedule like biweekly appeals to you, biweekly vs monthly payments works through the same math.
Where a Real Schedule Differs From This One
- Escrow. Your actual bill usually includes property tax and homeowners insurance. Those are not part of the amortization schedule, and they can change every year.
- Mortgage insurance. PMI is billed on top of principal and interest and does not amortize the loan. See how much PMI costs.
- Adjustable rates. On an ARM, the schedule is recalculated at every rate reset, so any schedule you see is only a projection. Compare structures in ARM vs fixed-rate mortgages.
- Rounding. Servicers round each month to the cent, so the last payment can differ slightly from the others.
How to Use Your Schedule: Four Steps
- Get the real one. Ask your servicer for the amortization schedule, or generate one in the mortgage calculator using the rate and term on your note.
- Find your balance row. Compare your servicer's current balance to the schedule's balance for the same payment number. On the example loan, after payment 60 the balance should read $374,444. A lower balance means extra payments were applied; a higher one is an error worth raising with your servicer.
- Test an extra amount. Pick a figure you could sustain and see the payoff date and interest saved.
- Plan around the crossover. If you expect to move or refinance before the principal share rises, estimate your balance at that date from the schedule rather than guessing.
Frequently Asked Questions
Does a 15-year mortgage amortize differently?
The method is identical, but the payment is larger and the balance falls faster. The same $400,000 at 6.50% over 15 years has a payment of $3,484 and total interest of $227,197, versus $510,178 over 30 years. Our 30-year vs 15-year comparison covers the trade-off.
Why is so much of my payment interest?
Interest is charged on the full outstanding balance each month. The balance is highest at the start, so interest takes the largest share then.
Does paying extra shorten the term or lower the payment?
By default it shortens the term, since the required payment stays the same. Lowering the payment requires a recast, explained in mortgage recast vs refinance.
Is the schedule the same for every lender?
For a standard fixed-rate loan with monthly compounding, the same loan amount, rate and term produce the same schedule, apart from cent-level rounding.
Bottom Line
A mortgage amortization schedule is simply a table of one formula applied 360 times. The key facts: the payment is fixed, interest is front-loaded, and anything you add toward principal early does the most work. Build yours in the mortgage calculator, then test an extra payment amount before deciding how to use your next raise or bonus.
This article is educational and uses illustrative rates, not a quote or personal advice. All schedule figures are MyCalcFinance calculations using the standard fixed-rate amortization formula with monthly compounding, excluding taxes, insurance, and PMI.