Follow the default numbers.
With current principal balance of $300,000, the model gives new payoff time: 243 months.
The formula is each payment reduces balance after monthly interest. Open the breakdown to trace expenses and assumptions. Change one input at a time to see how your decision changes. This example uses scenario inputs; it is not an offer, tax bill, appraisal or legal determination.
Extra principal reduces future interest
Each month’s interest is calculated on the outstanding balance. The scheduled payment pays that interest first, then principal; the extra payment reduces principal further. The tool compares the same loan with and without the extra amount and reconciles the final payment to the remaining balance. Escrow for taxes and insurance is outside the amortization.
The payoff date is a scenario
The number of modeled months assumes every extra payment arrives and is applied to principal. Changes in rate, skipped payments, fees or servicer timing can change the result. A fixed extra payment is different from a one-time curtailment; use the recast page for a lump-sum comparison. The annual table aggregates monthly amortization for easier review.
Verify payment application
Tell the servicer how additional money should be applied and check the next statement. Paying future installments in advance may not have the same effect as reducing principal immediately. Loan terms may impose conditions or penalties. Keep enough cash for other obligations before treating an interest-savings estimate as a complete household financial plan.
Keep your assumptions with the result
Save the calculation to your deal file to reuse compatible inputs in another tool. The file stays in this browser on this device. Download the CSV to open the complete inputs, results and schedule in Excel or Google Sheets. Use PDF to print the report or save it as a PDF. A share link includes entered financial figures in its URL, so use it only with people you intend to share those numbers with.