Mortgage Recast Calculator
See exactly how a lump-sum principal payment lowers your monthly payment and total interest — instantly, before you write the check.
Your Loan Details
Your outstanding principal balance today
The extra principal you plan to pay your lender
Typical range: $150–$500. Check with your servicer.
How a Recast Works
When you make a large lump-sum principal payment and request a recast, your lender re-amortizes your loan — the same rate, same term, but a lower balance — giving you a permanently lower monthly minimum payment without a full refinance.
Enter your loan details and click Calculate My Recast to see your savings.
Your Recast Results
Estimated refinance assumes same interest rate, a fresh 30-year term, and 2% closing costs. Actual refinance terms will vary based on your credit profile and market rates at time of application.
| Factor | Recast | Refinance (est.) |
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Annual amortization snapshot (end-of-year balances). Green row = recast year. Scroll horizontally on mobile to see all columns.
| Year | End Balance | Principal Paid | Interest Paid | Monthly Pmt |
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What Is a Mortgage Recast — and How Does It Work?
A mortgage recast, also called loan re-amortization, is a lender service that lets you make a large one-time payment toward your principal balance and then recalculate your monthly payments based on that new, lower balance — while keeping your original interest rate and remaining loan term exactly the same.
Unlike refinancing, a recast does not change your interest rate, does not extend your loan term, does not require a new appraisal, and does not trigger a hard credit pull. You simply pay down the balance, pay a small processing fee (typically $150–$500), and your lender re-amortizes the remaining balance across the remaining months at your existing rate — permanently reducing your required monthly minimum.
The core advantage: If you have come into money — a work bonus, inheritance, proceeds from selling another property, or a matured investment — a recast turns that windfall into permanent monthly cash flow relief without the cost, paperwork, and credit requirements of a full refinance.
Recast vs. Making an Extra Principal Payment (Without Recasting)
You can always send extra money to your principal without requesting a recast. Doing so reduces your balance and saves you interest — but your required monthly payment does not change. A recast does both: it reduces your balance and permanently lowers the monthly minimum you are contractually required to pay going forward. If monthly cash flow relief is part of your goal, you must submit a written recast request to your servicer along with the payment.
Which Loan Types Are Eligible for a Mortgage Recast?
Not every loan qualifies. Here is what most lenders require before approving a recast:
- Conventional loans (Fannie Mae / Freddie Mac) — generally eligible
- Jumbo loans — usually eligible, but lender-by-lender policy applies
- FHA loans — generally not eligible for recasting
- VA loans — generally not eligible for recasting
- USDA loans — generally not eligible for recasting
- Most lenders require a minimum lump-sum of $5,000–$10,000 above your normal monthly payment
- Your loan must be current with no missed or late payments
Always confirm eligibility with your loan servicer before sending your lump-sum payment. Some servicers do not offer recasting even on conventional loans, and the request process and minimum requirements vary significantly between lenders.
Step-by-Step: How to Request a Mortgage Recast from Your Lender
- Contact your loan servicer by phone and confirm in writing that your loan type is eligible for a recast (re-amortization). Ask for their written recast policy.
- Get the minimum payment requirement in writing. Most servicers require $5,000–$10,000 minimum above your regularly scheduled payment due that same month.
- Confirm the recast processing fee. Typical range is $150–$500. Some credit unions process recasts at no charge. Get this in writing before sending funds.
- Ask about processing time. Most servicers take 30 to 60 days to implement the new payment after receiving your funds and written request.
- Submit a written recast request along with your lump-sum payment. Use the servicer's secure online portal or certified mail, and retain copies of everything you send.
- Continue making your current payment until you receive written confirmation of the new amount. Any overpayment during the processing period goes straight to principal.
- Verify the new amortization schedule once your servicer sends it. Confirm the new monthly payment matches your calculation and that the balance reflects your lump-sum payment correctly.
Mortgage Recast vs. Refinance: Which Is the Better Move?
A Recast Makes More Sense When…
- Your current interest rate is already competitive with or below today's market rates
- You want to lower your monthly payment without resetting your loan's payoff timeline
- You have a large lump sum available from a bonus, inheritance, or asset sale
- You want to avoid refinancing costs (appraisal, origination fees, title insurance, credit pull)
- You are closer to payoff and don't want to restart a fresh 30-year amortization clock
- Your income or credit profile has changed since you took out the original loan
A Refinance Makes More Sense When…
- Current rates are meaningfully lower than your existing rate — typically at least 0.75 to 1% lower to justify closing costs
- You want to change your loan type — such as converting an ARM to a fixed rate or switching from 30 years to 15 years
- You need to access your equity through a cash-out refinance
- You have a government-backed loan (FHA, VA, USDA) that cannot be recast
- You want to remove private mortgage insurance (PMI) via a new appraisal showing higher home value
- Your credit score has significantly improved since you took out the original loan
Practical rule of thumb: If your current rate is within 1% of today's market rates, a recast almost always wins on total cost and simplicity. If current market rates are more than 1.5% below your rate, refinancing likely produces a better long-term outcome — but use the "vs. Refinance" tab in our calculator above to compare the numbers for your specific situation before deciding.
The Exact Math Behind a Mortgage Recast
Understanding the formula helps you verify your results and have an informed conversation with your servicer. The standard fixed-rate monthly payment formula used by all U.S. lenders is:
Where:
- M = monthly payment amount
- P = principal balance (this is the only value that changes in a recast — it decreases by your lump-sum amount)
- r = monthly interest rate (your annual rate divided by 12)
- n = total remaining number of monthly payments
In a recast, your lender applies this exact same formula with the same rate (r) and same remaining months (n), but uses your reduced principal balance (P − lump sum) as the new starting value. This calculator uses that same formula, so the results you see here should match your servicer's output precisely.
Example: $350,000 Loan at 6.5% with $50,000 Recast
Using default values: current balance $350,000, rate 6.5%, 25 years remaining, $50,000 lump sum:
- Original monthly payment: $2,363.23
- New balance after recast: $300,000
- New monthly payment: $2,025.62
- Monthly savings: $337.61
- Total interest saved over 25 years: $51,282