Mortgage Loan Recast Calculator






Mortgage Loan Recast Calculator | Save on Interest & Monthly Payments


Mortgage Loan Recast Calculator

Estimate your new lower monthly payment after a principal lump sum payment.


Your current outstanding mortgage principal.
Please enter a valid balance.


Your annual fixed interest rate.
Enter a rate between 0.1 and 20.


Number of years left on your current mortgage.
Please enter a valid number of years.


The amount you plan to pay toward the principal.
Lump sum cannot exceed balance.


Fee charged by your lender for the recasting process (typically $250-$500).


New Monthly Payment
$0.00
Monthly Savings
$0.00
Lifetime Interest Saved
$0.00
Old Payment
$0.00

Payment Comparison (Monthly)

Old Payment New Payment

Metric Before Recast After Recast
Monthly Principal & Interest $0 $0
Total Interest Paid $0 $0
Loan Balance $0 $0

Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]. Recasting uses the same rate (i) and remaining term (n) but reduces the principal (P).

What is a Mortgage Loan Recast Calculator?

A Mortgage Loan Recast Calculator is a specialized financial tool designed for homeowners who have a significant amount of cash—such as an inheritance, work bonus, or proceeds from a home sale—and want to lower their monthly housing costs without the complexities of refinancing. Unlike refinancing, which replaces your existing loan with a new one at current market rates, a mortgage recast keeps your current interest rate and loan term intact.

Who should use it? This tool is ideal for borrowers locked into low historical interest rates. If you have a 3% or 4% rate and want to reduce your monthly obligation, a Mortgage Loan Recast Calculator shows you exactly how much your payment will drop after applying a lump sum to your principal. It clears up the misconception that extra payments automatically lower your monthly bill; normally, extra payments only shorten the loan term unless you specifically request a “recast” or “re-amortization” from your lender.

Mortgage Loan Recast Calculator Formula and Mathematical Explanation

The math behind a mortgage recast is based on the standard fixed-rate amortization formula. The primary difference is that we calculate the payment twice: once for the current balance and once for the reduced balance after your lump sum payment.

The standard monthly payment formula is:

M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]

Variable Meaning Unit Typical Range
P Remaining Principal Balance USD ($) $50,000 – $1,000,000+
i Monthly Interest Rate (Annual Rate / 12) Decimal 0.002 – 0.007 (2.5% – 8%)
n Remaining Months on Loan Months 12 – 360 months
M Monthly Payment USD ($) $500 – $5,000

Practical Examples (Real-World Use Cases)

Example 1: The “Inheritance” Scenario

Imagine you have a $400,000 balance on a 30-year mortgage with 20 years (240 months) remaining. Your interest rate is 5%. Your current payment is approximately $2,640. You receive a $100,000 inheritance. By using the Mortgage Loan Recast Calculator, you discover that after paying a $250 fee and applying $100,000 to the principal, your new balance is $300,000. Your new monthly payment drops to roughly $1,980. You save $660 every single month for the next 20 years.

Example 2: The “Downsizer” Scenario

A couple sells a vacation home and nets $50,000. They have $200,000 left on their primary mortgage at 6% with 15 years remaining. Their current payment is $1,687. After a recast with the $50,000 lump sum, the Mortgage Loan Recast Calculator shows the new payment will be $1,265. This $422 monthly savings allows them to fund their retirement accounts more aggressively while keeping their low 6% rate from five years ago.

How to Use This Mortgage Loan Recast Calculator

  1. Enter Current Balance: Look at your most recent mortgage statement to find your “unpaid principal balance.”
  2. Input Interest Rate: Enter your annual percentage rate (APR). This remains unchanged during a recast.
  3. Remaining Term: Calculate how many years or months you have left until the loan is fully paid off.
  4. Lump Sum Amount: Enter the total cash amount you intend to pay toward the principal.
  5. Lender Fee: Most banks charge a small administrative fee (usually $250 to $500) to process a recast.
  6. Analyze Results: The Mortgage Loan Recast Calculator will instantly update your new payment, monthly savings, and the total interest you’ll save over the remaining life of the loan.

Key Factors That Affect Mortgage Loan Recast Calculator Results

  • Interest Rate: Higher rates lead to more significant monthly payment reductions for every dollar of principal paid down.
  • Remaining Term: The longer the remaining time on your loan, the more the lump sum is “stretched” over the amortization schedule, resulting in lower monthly payments but potentially less dramatic interest savings than a shorter term.
  • Lump Sum Size: Most lenders require a minimum (e.g., $5,000 or 10% of balance) to trigger a recast. Larger sums yield larger savings.
  • Lender Participation: Not all loan types (like FHA or VA in some cases) allow for recasting. Always check with your servicer first.
  • Opportunity Cost: Before recasting, consider if that lump sum could earn a higher return in the stock market compared to your mortgage interest rate.
  • Inflation: In high-inflation environments, carrying low-interest debt might be mathematically preferable to paying it down early.

Frequently Asked Questions (FAQ)

1. Does a recast change my interest rate?

No. One of the main benefits of using a Mortgage Loan Recast Calculator is seeing how you can lower your payment while keeping your original, potentially low interest rate.

2. Is a recast the same as a refinance?

No. Refinancing involves getting a brand-new loan with new terms and rates. Recasting simply re-calculates your current loan based on a smaller balance.

3. How much does a mortgage recast cost?

Typically, lenders charge between $250 and $500. This is significantly cheaper than refinancing, which can cost 2-5% of the loan amount in closing costs.

4. Can I recast an FHA or VA loan?

Generally, FHA and VA loans do not permit recasting. Recasting is most common with conventional fixed-rate mortgages held by Fannie Mae or Freddie Mac.

5. Will recasting shorten my loan term?

No. Recasting lowers your monthly payment but keeps the original payoff date. If you want to shorten the term, you should simply make extra principal payments without recasting.

6. Is there a minimum lump sum required?

Yes, most banks require at least $5,000 to $10,000, though requirements vary by lender. Use our Mortgage Loan Recast Calculator to see if your intended amount makes a meaningful difference.

7. How many times can I recast my mortgage?

Most lenders allow it as often as you meet their minimum lump sum requirements, but some may limit it to once per year or once over the life of the loan.

8. Does recasting require a new credit check or appraisal?

Usually, no. Since you aren’t taking out a new loan, lenders typically do not require a credit pull or a new home appraisal.


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