Financial mathematics · Laboratory
Mortgages and loan amortization
Same principal, rate and term: explore how the repayment method changes payments and interest.
Read the step-by-step explanationCompare the four options
Two versions of the French schedule, plus Italian and principal-at-maturity schedules. All options use the same inputs; the two French versions differ only in rounding.
How the outstanding balance falls
- French · no intermediate rounding
- French · level payments rounded to cents
- Italian · equal principal
- Principal at maturity · bullet
Each line shows debt after payment. Under the bullet method, the principal stays unchanged until the last payment.
Inside one payment
Complete amortization schedule
No intermediate rounding: calculations retain decimals while the table displays cents. Totals are calculated before rounding, so adding displayed amounts can produce small differences. Interest / principal = total interest ÷ original principal × 100%: this covers the whole term, not one year.
Remaining interest is the sum of interest in this schedule’s future payments: it is not accrued interest or an amount necessarily payable on early repayment.
| Payment no. | Opening balance | Payment | Interest | Principal repaid | Remaining interest | Closing balance |
|---|
Further reading: Bank of Italy — mortgage payments and borrowing costs