Mortgage Recast Calculator
Estimate your new monthly payment and interest savings after making a principal reduction payment.
Payment Comparison
Comparing current monthly obligation vs. new obligation after mortgage recast.
Comparison Summary Table
| Metric | Before Recast | After Recast | Difference |
|---|
What is a Mortgage Recast?
A mortgage recast calculator is an essential tool for homeowners who have a significant amount of cash and want to lower their monthly financial obligations without the high costs of refinancing. Unlike refinancing, where you replace your old loan with a new one (often at a new interest rate), a mortgage recast keeps your existing interest rate and term intact. Instead, you pay a large lump sum toward your principal, and your lender “re-amortizes” the remaining balance over the remaining months of your loan.
Many people use a mortgage recast calculator when they have sold a previous home, received an inheritance, or reached a major savings milestone. It is a lower-cost alternative to refinancing, usually involving a small administrative fee rather than thousands in closing costs. Who should use it? Homeowners with a low interest rate who want to reduce their monthly “burn rate” while keeping their favorable loan terms.
Mortgage Recast Calculator Formula and Mathematical Explanation
The math behind a mortgage recast calculator relies on the standard amortization formula, applied twice. First, it calculates the current payment, and second, it calculates the new payment using the adjusted principal balance.
The standard monthly payment formula is:
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
Where:
| Variable | Meaning | Unit | Typical Range |
|---|---|---|---|
| P | Remaining Principal Balance | USD ($) | $50,000 – $1,000,000 |
| i | Monthly Interest Rate (Annual Rate / 12) | Decimal | 0.002 – 0.007 |
| n | Remaining Months in Term | Months | 12 – 360 |
| M | Monthly Principal & Interest Payment | USD ($) | $500 – $6,000 |
Practical Examples (Real-World Use Cases)
Example 1: The “New Home Sale” Scenario
Imagine you bought a new house before selling your old one. You have a $500,000 mortgage at 6% interest with 28 years left. Once your old home sells, you have $100,000 in net proceeds. By using the mortgage recast calculator, you see that your payment drops from roughly $3,083 to $2,466. This saves you $617 every single month, significantly improving your cash flow.
Example 2: The Windfall Scenario
A homeowner has a $200,000 balance at 4% with 15 years remaining. They receive a $50,000 bonus and want to lower their expenses. The mortgage recast calculator shows the payment dropping from $1,479 to $1,109. Over the next 15 years, they also save approximately $13,500 in total interest because the principal was reduced early.
How to Use This Mortgage Recast Calculator
Follow these steps to get an accurate estimate of your savings:
- Current Loan Balance: Look at your most recent mortgage statement to find your exact principal balance.
- Interest Rate: Enter your current annual fixed interest rate.
- Remaining Term: Calculate how many years are left on your mortgage. If you have 22 years and 4 months, you can use 22.33.
- Lump Sum Payment: Enter the amount of cash you plan to pay toward the principal.
- Recast Fee: Call your lender to ask if they offer recasting and what the fee is. It is usually between $200 and $500.
The results will update in real-time, showing your monthly savings and the long-term interest impact.
Key Factors That Affect Mortgage Recast Calculator Results
- Interest Rate: Higher interest rates result in larger monthly payment drops for the same lump sum because the “cost” of that principal was higher.
- Remaining Term: The longer the remaining term, the more a lump sum payment will spread out the savings over time.
- Lump Sum Size: Most lenders require a minimum of $5,000 to $10,000 for a recast. The larger the sum, the lower the new payment.
- Lender Participation: Not all lenders offer recasting. FHA and VA loans generally do not allow for recasting, while most conventional loans do.
- Timing: Recasting early in the loan term results in more total interest savings than recasting near the end.
- Recast Fee: While small, the fee is a “sunk cost” that should be subtracted from your first few months of savings to find your break-even point.
Frequently Asked Questions (FAQ)
No, a recast keeps your original interest rate. To change your rate, you would need to use a refinance vs recast comparison.
Yes. If you have 20 years left, you will still have 20 years left after the recast. The monthly payment is simply lowered so that the loan still finishes on the original end date.
Making extra mortgage payments reduces your principal and shortens the life of the loan, but your required monthly payment stays the same. A recast forces the lender to lower your required monthly payment.
Usually, no. Most government-backed loans do not have recasting provisions. It is primarily a feature of conventional mortgages.
Generally, no. Since you aren’t applying for a new loan, lenders usually do not require a credit check or a new appraisal.
If you need better monthly cash flow, use a mortgage recast calculator. If you want to pay off the house as fast as possible, just make a principal reduction payment without recasting.
It typically takes 30 to 60 days for the lender to process the paperwork and for the new payment amount to reflect on your statement.
Probably not. Since there is a fee, you might not save enough in monthly payments to cover the fee before you sell. Use a home equity calculator to see your proceeds instead.
Related Tools and Internal Resources
- Mortgage Amortization Calculator: View your full payment schedule and interest breakdown.
- Principal Reduction Calculator: See how much time you save by paying extra.
- Extra Payment Calculator: Model different monthly or yearly extra payments.
- Mortgage Payoff Calculator: Find out exactly when you will be debt-free.
- Refinance vs Recast Comparison: Decide which strategy is best for your current rate.
- Home Equity Calculator: Track how much of your home you actually own.