Amortization schedule explained

An amortization schedule is a row-by-row table showing every monthly payment on a loan, split into principal, interest, and remaining balance. It is the most useful single document for understanding a loan because it reveals patterns that the monthly payment alone hides: when interest stops dominating, how slowly the balance falls at the start, and how much each scheduled payment actually reduces what you owe.

This guide explains every column you'll see, walks through a worked schedule excerpt, shows how to read the schedule for decision-making, and answers common questions about why the math works the way it does.

What "amortization" means

Amortization comes from the Latin ad mortem — "to death." For a loan, it means killing the balance gradually through a fixed schedule of equal payments. Each payment combines two things:

• Interest on the remaining balance, calculated from the current balance × monthly rate.
• Principal, which is the rest of the payment after interest is deducted. Principal reduces the balance for next month.

Because the balance falls every month, the interest portion of each payment also falls, and the principal portion grows. The total payment stays the same — but the split changes month by month.

The columns in a typical schedule

A standard amortization schedule has six columns:

• Payment number — sequential number from 1 to the total number of payments (e.g., 360 for a 30-year mortgage).
• Payment date — the scheduled due date for that payment.
• Total payment — the fixed monthly amount (principal + interest, sometimes including tax and insurance escrow).
• Principal paid — the portion of the payment that reduces the loan balance.
• Interest paid — the portion of the payment that goes to the lender as the cost of borrowing.
• Remaining balance — what you still owe after this payment.

Some schedules also include a cumulative interest column (running total of all interest paid to date) and a cumulative principal column (running total of all principal paid to date).

Worked example: first year of a $240,000 30-year mortgage at 6.5%

The "crossover point" — when principal exceeds interest

Early in any amortizing loan, most of each payment is interest. As the balance falls, less interest is charged and more of the payment becomes principal. The month when principal first exceeds interest is called the crossover point.

On a 30-year mortgage at 6.5%, the crossover point is around month 217 (year 18). On a 15-year mortgage at the same rate, it happens much earlier — around month 87 (year 7). On a 60-month auto loan at 7.5%, it happens around month 32. Shorter loans hit the crossover faster because more of each payment is principal from the start.

How the balance curve looks

If you plot the loan balance over time, you get a downward curve that starts almost flat and steepens over time. The first few years barely move the needle. The last few years drop quickly. This shape is the visual signature of amortization.

By the halfway point of a 30-year mortgage (year 15), you've typically paid down only about 30% of the original balance. The other 70% gets paid in the second half — and the final five years pay down almost as much principal as the first 20 years.

How extra payments change the schedule

When you make extra payments toward principal, every row after that payment gets recalculated:

• The balance is lower than the original schedule would show.
• Interest on subsequent payments is calculated on the lower balance, so each future interest charge is smaller.
• More of each future monthly payment goes to principal (since less is needed for interest).
• The loan reaches zero earlier — saving the months that would otherwise have been at the end of the schedule.

See our extra payment guide for worked examples showing how small extra payments compound into large interest savings.

How to use an amortization schedule for decisions

Beyond satisfying curiosity, a schedule helps with concrete decisions:

• "How much equity will I have in 5 years?" Look at the balance after 60 payments. The difference between the original loan and that balance is the equity you've built through principal payments (separate from price appreciation).
• "What will I owe if I sell in 10 years?" Look at the balance after 120 payments. That tells you the payoff amount you'd need to clear at closing.
• "How much will I save by paying extra?" Compare cumulative interest in the original schedule vs the extra-payment schedule.
• "Should I refinance?" Look at where you are in the schedule. Early in the loan (when you're paying mostly interest), refinancing to a lower rate has a bigger impact. Late in the loan, you're paying mostly principal anyway and refinancing helps less.
• "What's my tax-deductible interest this year?" Sum the interest column for 12 months. For US mortgages, this is typically reported on Form 1098 by the lender but you can sanity-check.

Why the monthly payment stays the same

The standard amortization formula is designed to produce a fixed monthly payment that pays off the loan exactly at the end of the term. The math works backward — given a starting balance, rate, and term, the formula solves for the monthly payment that makes the final balance zero.

Variable-rate loans use a similar approach but recalculate the payment when the rate changes. Interest-only loans skip principal during the interest-only period — but eventually have to amortize the balance over a shorter remaining term.

Common schedule misconceptions

• "My early payments are mostly interest because the lender front-loads interest." Not quite. The lender is not "front-loading" anything. Interest is high at the start because the balance is high. The math falls out naturally from the formula.
• "If I make half the payments, I've paid off half the loan." No. On a 30-year mortgage, after 180 payments (half the term), you've typically paid off only about 30% of the principal.
• "Extra payments just go to interest." They should go to principal if you tell the lender that. See the extra payment guide for instructions on how to ensure that.
• "The schedule guarantees what I'll pay." Variable-rate loans, escrow adjustments, late fees, and refinancing can all change the schedule. The original schedule is a starting reference, not a contract.

Why export the schedule to CSV

A 30-year mortgage has 360 rows. Reading them on a web page is impractical. Exporting to CSV lets you:

• Open the schedule in Excel, Google Sheets, or Numbers for filtering and analysis
• Compare two scenarios side by side
• Plot the principal/interest split over time
• Calculate cumulative interest for tax planning
• Archive a snapshot of your loan terms for your own records

Get Loan Calc's on-page preview shows the first year for readability. The CSV export contains every row of the full schedule.

Frequently asked questions