An amortization schedule looks intimidating at first: dozens of rows, a handful of columns, and a mountain of numbers. Strip away the formatting and it is remarkably simple. Every row has the same structure, and once you see it once, you can read any schedule.
The anatomy of one row
Each row of an amortization schedule describes a single payment and contains three useful numbers: the interest charged on that month's balance, the principal repaid, and the balance left afterward. The three are related by one rule:
Payment = interest + principal, and new balance = old balance − principal.
Interest always comes first because it is computed on the balance at the start of the month. Whatever portion of the payment is left over reduces the principal.
A small worked example
Take a $10,000 loan at 6% annual interest over 36 months. The monthly rate is 6% ÷ 12 = 0.5%, and the fixed monthly payment works out to about $304.22.
| Month | Payment | Interest | Principal | Balance |
|---|---|---|---|---|
| Start | — | — | — | $10,000.00 |
| 1 | $304.22 | $50.00 | $254.22 | $9,745.78 |
| 2 | $304.22 | $48.73 | $255.49 | $9,490.29 |
| 12 | $304.22 | ~$36.00 | ~$268.00 | ~$7,173.00 |
| 36 | $304.22 | ~$1.51 | ~$302.71 | $0.00 |
Reading the pattern
Notice how the interest column shrinks month by month. In month one, $50 of the $304.22 payment is interest and only $254.22 reduces principal. By year three, the split has flipped dramatically: nearly the whole payment goes to principal and very little to interest.
This is the signature of front-loaded interest. The balance is largest early, so interest is largest early. The payment never changes, but the ratio inside it keeps shifting from mostly-interest to mostly-principal.
Why the balance column matters
The balance column is your real position. It is what you would owe today if the loan were closed out. Because interest is always charged on that balance, the balance is also what drives the next row's interest figure. Watch this column if you ever want to track progress or plan a payoff.
If you spot a prepayment, the balance column is where you see the effect, because extra money reduces the starting balance of every remaining row.
Three things to verify in any schedule
When a lender hands you a schedule, check that three things line up. First, the last balance is exactly zero, meaning every payment was accounted for. Second, the interest column totals match the total interest quoted for the loan. Third, the first rows hold the largest interest amounts, confirming interest is being added to the outstanding balance rather than charged upfront.
Practice with your own loan
Generate a schedule for your own amount, rate and term, and watch the principal-versus-interest split change over time with the LoanMetra loan calculator.