Home Loan Extra Payments Calculator with Extra Payments

Calculations use the standard fixed-rate mortgage amortization formula to compute the scheduled monthly payment and then recompute payoff duration when extra principal payments are applied.

Recurring extra payments are modeled as an additional fixed amount added to each monthly payment. One-time payments are modeled as an immediate principal reduction. Annual lumps are approximated by an equivalent monthly amount (annual amount divided by 12).

Outputs are rounded to whole months for payoff timing estimates; intermediate expressions use continuous math functions and natural logarithms to compute the exact number of payments before rounding.

Use recurring extra payments to see ongoing reduction in interest and term. One-time payments are effective at reducing principal immediately but will usually save less interest than the same amount paid regularly over time.

Results are approximations and assume consistent application of extra payments toward principal. Check your loan agreement for prepayment rules and verify results with your loan servicer.

Example: $300,000 loan at 4.00% for 30 years. Paying an extra $200/month reduces the payoff period and saves interest; the calculator shows estimated months to payoff, years shaved, and interest saved.

Example: A $1000 one-time payment applied at the next payment reduces principal and shortens the amortization schedule; the tool approximates the effect by recomputing payoff with the reduced principal.