- Mortgage recast
- A lender recalculation of your monthly payment after you pay a lump sum toward principal. The interest rate and payoff date stay the same; only the payment drops, because a smaller balance is spread over the remaining term. Not every loan allows it, and lenders often set a minimum lump sum and charge a fee.
- Lump sum payment
- A single extra payment applied directly to principal before the payment is recalculated. In this calculator it is subtracted from the current balance to find the new balance. The larger the lump sum relative to the balance, the larger the drop in payment and in future interest.
- Principal balance
- The amount you still owe on the mortgage, excluding future interest. It appears on your monthly statement and is lower than the original loan amount because each payment has repaid some principal. Interest each month is charged on this balance, so reducing it reduces every future interest charge.
- Amortization
- The schedule by which equal payments pay off a loan over a set term, with early payments weighted toward interest. A recast re-amortizes the loan: it builds a new schedule from the reduced balance over the years remaining, which produces the lower payment this calculator shows.
- Recast fee
- An administrative charge some servicers apply to process a recast. It is usually modest compared with refinancing costs, but it varies by servicer and is not included in this calculator’s results. Subtract it from the interest saved to see the net benefit, and confirm the fee and minimum lump sum with your servicer.
- Refinance
- Replacing your mortgage with a new loan, often to change the rate or term or to take cash out. Unlike a recast, it requires a new application, underwriting and closing costs, and it can lower your interest rate. A recast keeps your existing rate, so it suits borrowers who already have a rate they want to keep.
- Interest saved
- The reduction in total interest over the remaining term that results from paying down principal with the lump sum. The saving comes from the principal reduction itself, not from the recast; applying the same lump sum without recasting saves at least as much interest but keeps the old payment and shortens the payoff instead.
- Remaining term
- The number of years left until the mortgage is scheduled to be paid off. A recast keeps this unchanged and spreads the new, smaller balance across it. The longer the remaining term, the smaller the payment drop per dollar of lump sum, because the reduction is spread over more payments.
