Mortgage Recast Calculator
Put a lump sum toward principal and re-amortize — see your lower monthly payment after a mortgage recast without changing the rate or term.
How it works
New balance = balance − lump sum · New payment = newBal·r ÷ (1 − (1+r)^−n), same n and rate · Interest saved = (oldPay·n − bal) − (newPay·n − newBal)
A recast keeps your rate and remaining term but re-amortizes the loan around a smaller principal after a lump-sum payment. The result is a permanently lower monthly payment for the same payoff date. Unlike a refinance there is no new loan, no credit check and usually only a small recast fee — but the interest rate stays exactly what it was.
Worked example
On a $260,000 balance at 6% with 25 years left, the payment is about $1,675. Pay $40,000 down and the lender re-amortizes the remaining $220,000 over the same 25 years, cutting the payment to about $1,418 — roughly $257 less a month.
Frequently asked questions
How is a recast different from a refinance?
A recast re-amortizes your existing loan around a lower balance, keeping the same rate and term with only a small fee. A refinance replaces the loan entirely with a new rate, term and closing costs. Recast when you have cash and a good rate; refinance when you want a lower rate.
Does a recast shorten my loan?
No. A standard recast keeps the same payoff date and lowers the monthly payment. If you want to keep the same payment and finish early instead, make the lump-sum payment without recasting and let the term shrink.
Are all loans eligible?
Most conventional loans allow recasting, usually with a minimum lump sum (often $5,000–$10,000) and a fee around $150–$500. FHA, VA and USDA loans generally cannot be recast. Check with your servicer first.
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Educational estimate only — not financial, tax or lending advice. Confirm exact figures with your lender.