US Mortgage Extra-Payment Planner
Compare modeled mortgage interest and payoff months with recurring extra principal; download both schedules as CSV.
Tool inputs stay in your browser · optional AI search sends your query
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Good to know: Independent ToolsKo estimate. Sources reviewed November 11, 2026. For current fixed-rate, fully amortizing monthly loans in good standing. Recomputes a modeled principal-and-interest payment from current principal, rate and remaining months; it does not read or reproduce your contractual payment. Applies extra principal with every monthly payment starting next modeled month, no recast. Interest and payment round to cents monthly; the final scheduled payment clears rounding residue. Excludes escrow, taxes, insurance, PMI, fees, arrears, daily-interest loans, adjustable rates and prepayment penalties. Confirm principal-only instructions and any restrictions with your servicer. No calendar payoff date or lender payoff quote is provided.
How to use it (step by step)
- 1Enter current unpaid principal, annual contract interest rate and remaining number of monthly payments. Exclude escrow from the principal balance.
- 2Choose the extra principal you would pay with every monthly payment, then compare modeled interest and months saved.
- 3Download both schedules and confirm the servicer will apply extra money to principal. Actual contractual payments, timing and charges can change the result.
Words to know
- Principal
- The outstanding borrowed amount before interest, escrow or fees.
- Amortization
- The payment-by-payment split between interest and reduction of principal.
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Sources & methods
References checked November 11, 2026. Read each tool’s scope and assumptions before relying on its result.