An amortisation schedule lists every payment on a loan in order and splits each one into interest and principal, with the balance left after it. The last row's balance is zero, and the interest column added up is the total cost of borrowing. The CFPB gives the same name to the chart showing how much of each payment goes to principal and how much to interest.
Each row follows from the one before. Interest is the opening balance times the rate per period, rounded to the cent; the principal repaid is the payment minus that interest; the closing balance is the opening balance minus the principal repaid. For £10,000 at 6% over five years, paid at £193.33 a month, the first two rows and the last read:
| Month | Interest | Principal | Balance left |
|---|---|---|---|
| 1 | £50.00 | £143.33 | £9,856.67 |
| 2 | £49.28 | £144.05 | £9,712.62 |
| 60 | £0.96 | £192.25 | £0.00 |
The final payment is £193.21, a few pence below the rest, because rounding in the earlier rows left slightly less to clear. The schedule settles that difference in the last row, which is why a schedule built from rounded rows never quite equals 60 × £193.33.
A schedule also shows what a lump sum would do. Overpay in month 12 and every later row starts from a lower balance, so either the term shortens or the payment falls, depending on what your lender offers. Reading down the principal column is the quickest way to see how slowly the balance of a long mortgage falls in its first years.
The loan calculator builds the full schedule by month or by year, and the mortgage calculator shows one for principal and interest only, with tax and insurance kept off the table.