Mortgage Payoff Calculator

What this mortgage payoff calculator does

It takes the loan you already hold — not a new one — and tells you how much longer it will run at your current payment, along with the interest still to come. That second number is what makes overpayment decisions concrete: the interest you avoid is money you keep, and on a mortgage the amounts involved are usually larger than any other saving decision you will make.

The formula behind it

The remaining months are −log(1 − B × r ÷ P) ÷ log(1 + r), where B is your remaining balance, r the monthly rate and P your monthly payment. Total remaining interest is the sum of those payments minus the balance. Because the term sits inside a logarithm, small increases in payment produce disproportionately large reductions in time.

How to use this calculator

Enter your remaining balance, your interest rate and the monthly payment you actually make. The result shows the years and months left and the total interest still ahead. Add a modest amount to the payment and run it again — an extra 10% often removes several years and a large share of the remaining interest.

Should you overpay?

Overpaying a mortgage earns you a guaranteed, tax-free return equal to your interest rate, which is a strong result when rates are high. Compare that rate against what the same money would earn invested, and against clearing any higher-rate debt first — card debt at 20% always outranks a mortgage at 5%. Check for early-repayment charges, and keep an accessible emergency fund: money paid into a property is difficult to retrieve when you need it.