Enter your current mortgage balance, interest rate, remaining term, and lump-sum payment to see your new monthly payment, monthly savings, and total interest reduction after a recast.
Current Mortgage
$
%
yr
mo
Recast Details
$
Amount applied to principal before re-amortization.
$
Typically $150–$500. Leave blank if waived.
Recast Analysis
Monthly Payment
Original monthly payment$0.00
Recast balance (after payment)$0.00
New monthly payment$0.00
Monthly payment reduction$0.00
Total Interest (Remaining Term)
Original remaining interest$0.00
New total interest$0.00
Interest savings$0.00
Net savings (after recast fee)$0.00
New Payment
$0.00
Monthly Savings
$0.00
Interest Saved
$0
Estimates assume same interest rate and remaining term. Not all lenders offer recasting. Actual results depend on servicer eligibility rules and fees.
About the Mortgage Recast Calculator
A mortgage recast is one of the most underutilized tools in personal finance. If you come into a lump sum — from a bonus, inheritance, home sale proceeds, or savings — applying it as a principal payment and requesting a recast can permanently lower your required monthly payment without the time, cost, and qualification hurdles of refinancing. This calculator shows you exactly how much your payment drops and how much total interest you save.
How a Recast Works
When you recast, your lender takes your reduced principal balance and re-amortizes the loan using the same interest rate and the same remaining term. The formula is straightforward:
Recast Balance = Current Balance − Lump-Sum Payment
New Monthly Payment = Recast Balance × [r(1+r)ⁿ] / [(1+r)ⁿ − 1]
Monthly Savings = Original Payment − New Monthly Payment
Where r is the monthly interest rate (annual rate ÷ 12) and n is the remaining term in months.
Recast vs. Refinance
Recast — same loan, same rate, same lender, lower payment. Typically costs $150–$500 and requires no credit check.
Refinance — new loan with potentially different rate and term. Costs 2–5% of the loan amount in closing costs and requires full underwriting.
Recasting makes the most sense when your existing rate is competitive and you don't want to reset your loan term or pay refinancing costs.
When to Use This Calculator
Bonus or windfall — evaluate whether to apply a year-end bonus, inheritance, or sale proceeds to your mortgage principal
Comparing with prepayment — understand that extra principal payments reduce future interest but don't lower your required monthly payment without a recast
Refinancing alternative — if your current rate is already low, a recast avoids closing costs while still reducing your monthly obligation
Cash flow planning — quantify the monthly budget relief a recast provides before committing a large cash sum
Not all lenders offer mortgage recasting. FHA, VA, and USDA loans typically do not qualify. Conventional loans often do, but eligibility, minimum payment requirements, and fees vary by servicer. Always confirm with your lender before making a large principal payment. Not financial advice.
Frequently Asked Questions
What is a mortgage recast?
A mortgage recast (also called re-amortization) is when you make a large lump-sum payment toward your mortgage principal and your lender recalculates your monthly payment using the reduced balance, the same interest rate, and the same remaining loan term. Unlike extra principal payments, which don't lower your monthly payment, a recast formally restructures your payment schedule — so your required monthly payment drops permanently.
How is recasting different from refinancing?
Refinancing replaces your mortgage with an entirely new loan — new interest rate, new term, new closing costs, and often a credit check and full underwriting process. Recasting keeps your existing loan intact: same rate, same lender, same remaining term. You just make a large principal payment and the lender re-amortizes the balance. Recasting is typically much simpler, faster, and cheaper — most lenders charge a one-time fee of $150–$500 versus thousands in refinancing costs.
How much can a recast lower my monthly payment?
It depends on the size of your lump-sum payment relative to your remaining balance and your remaining term. A $50,000 payment on a $400,000 balance at 7% with 300 months remaining reduces the monthly payment by roughly $350. Use this calculator to model your exact scenario — the larger the payment and the longer the remaining term, the bigger the monthly reduction.
Does a recast save interest?
Yes. When you reduce the principal balance, you pay interest on a smaller amount for the same number of remaining months. The total interest savings equals the difference between what you would have paid over the remaining term on the original balance versus the recast balance. This calculator shows both figures so you can see the full long-term benefit.
Can a recast fully pay off my mortgage?
Yes. If your lump-sum payment equals or exceeds the remaining balance, the mortgage is fully paid off. There is nothing left to recast. This calculator shows a note when your lump-sum payment covers the full balance.
Do all lenders allow mortgage recasting?
No. Recasting is not available on all loan types or with all lenders. FHA, VA, and USDA loans typically do not allow recasting. Conventional loans often do, but servicers have the final say. Most lenders require a minimum lump-sum payment (commonly $5,000–$10,000) and may have waiting periods. Always confirm recast availability, fees, and eligibility rules with your specific servicer before making a large payment.
Is this calculator different from a refinance calculator?
Yes. A refinance calculator models replacing your mortgage with a new loan at a new rate and term — including closing costs and break-even analysis. This recast calculator keeps your rate and term fixed, adjusting only the principal. Use this tool when you want to evaluate the impact of a large principal payment on your current loan without the complexity of refinancing.
