Three repayment methods, same inputs
Enter the amount, rate and term, then switch methods to see how much total interest changes.
| Method | Monthly amount | Total interest |
|---|---|---|
| Equal payment | Same every month | Middle |
| Equal principal | Highest first, then falls | Lowest |
| Interest-only | Interest, principal at maturity | Highest |
Add a grace period and only interest is charged during it.
Period-by-period schedule
The table shows how each payment splits between principal and interest. Rounding is absorbed by the final period so the balance lands exactly on zero. Export to CSV and it opens straight in Excel.
Excel formulas, prefilled
The formulas are shown with your own numbers already substituted, ready to paste into a sheet.
- Monthly payment:
=PMT(rate%/12, nper, -principal) - Principal in period n:
=PPMT(rate%/12, n, nper, -principal) - Interest in period n:
=IPMT(rate%/12, n, nper, -principal)
Equal-principal and interest-only switch to plain arithmetic formulas.
Note
Real invoices vary with your lender’s interest convention and any prepayment fees. This is a planning estimate, not a quote.