Loan entry
Applied straight to principal, every period.
Ledger reads
Paid in full$0
per month, principal & interest
- Payoff date
- —
- Time saved
- —
- Total of payments
- $0
- Total interest cost
- $0
Where the money goes
Cumulative principal crosses cumulative interest at month —.
Full schedule
Every month is listed, grouped by annual period — click a year to open or close it. Add a one‑time extra principal payment to any month in the extra column, and every month after it recalculates automatically: lower balances, less interest, an earlier payoff.
| Date | Period | Payment | Principal | Interest | Extra | Balance |
|---|
How the numbers work
Your monthly payment here covers principal and interest only — the two parts of a mortgage that follow strict math. It doesn't include property taxes, homeowner's insurance, PMI, or HOA dues, since those vary by lender, location, and policy. Ask your lender for the full PITI figure before you budget against this number.
Early in a loan, most of each payment goes to interest, because interest is charged on whatever balance is still outstanding, and the balance starts at its highest point. As the balance shrinks, less of each payment is eaten by interest and more goes to principal — that's the "crossover" the chart marks: the month your payments start doing more work for you than for the lender.
Extra payments shrink the balance directly, which means every payment after an extra one is calculated against a smaller number — so it compounds. A single early lump sum often saves more in total interest than the same amount spread thin over many months, simply because it starts working sooner.
Is this the same as what my lender will quote me?
It's a close estimate for a standard fixed-rate loan compounded monthly. Lenders may round differently, add fees, or quote APR instead of the note rate — treat this as planning, not a binding number.
Does it handle adjustable-rate mortgages (ARMs)?
No — this calculator assumes one fixed rate for the full term. For an ARM, you'd need to re-run the numbers with the new rate each time it adjusts.
What happens to the "extra payment" numbers if I change the loan amount or rate?
One-time extra payments you've entered in the table stay in place by period number. If you want a clean slate, use "Clear extra payments" above the schedule.
Is anything I enter saved or sent anywhere?
No. Every calculation runs in your browser. Nothing you type is transmitted to a server or stored — refreshing the page resets it. See the privacy policy for how ads on this site work.
This tool is for general planning purposes only and isn't financial, legal, or lending advice. Speak with a licensed mortgage professional before making borrowing decisions.