See how a lump-sum payment plus a recast lowers your monthly mortgage payment without changing your rate or term.
Recast keeps your original rate and term; only the remaining balance is re-amortized after the lump sum.
A recast is the underused sibling of the refinance. You apply a lump sum to principal and the lender re-amortizes the remaining balance over the remaining term at your existing rate — same rate, same payoff date, lower monthly. No credit check, no closing costs beyond a small recast fee.
New Balance = Current Balance − Lump Sum. New Monthly = New Balance × r / (1 − (1+r)^−n), where r = rate/12 and n = remaining months. Interest saved = (Old total interest − New total interest) − Recast fee.
A $300,000 balance at 6.5% with 25 years remaining costs about $2,025/month. A $50,000 lump sum reduces the balance to $250,000; the recast drops the monthly to about $1,688 — a $337/month drop — and saves roughly $101,000 in total interest.
Estimate your monthly mortgage payment including principal, interest, property taxes, insurance, HOA, and PMI.
See the maximum home price you can responsibly afford based on income, debts, down payment, and current rates.
Calculate monthly savings, break-even point, and lifetime interest if you refinance your mortgage.
Mortgage calculator with extra payments to principal — see how much interest and time you save by adding an extra monthly principal payment.
Most conforming (conventional) loans allow it. FHA, VA, and USDA typically don't. Ask your servicer.
Often $5,000–$10,000 minimum, but this varies by servicer.
Extra payments save the same interest and shorten the term. Recast trades term shortening for lower required monthly payments — better for cash-flow flexibility.
This calculator is for educational and estimation purposes only. It does not provide financial, mortgage, tax, investment, or legal advice. Actual rates, payments, taxes, fees, insurance costs, eligibility, and loan terms vary by lender, location, credit profile, and market conditions. Always compare official offers and consult a qualified professional before making financial decisions.
Last updated June 2026 · Prepared by the mCalculator Editorial Team