Mortgage Recast Calculator

Estimate your new monthly payment after making a principal reduction payment.

What is a Mortgage Recast Calculator?

A mortgage recast calculator is a specialized financial tool designed to help homeowners determine how a lump-sum principal payment will affect their monthly mortgage obligation. Unlike refinancing, which replaces your existing loan with a new one, a mortgage recast (or re-amortization) keeps your current interest rate and loan term intact but recalculates your monthly payments based on the lower principal balance.

Who should use a mortgage recast calculator? This tool is essential for individuals who have recently come into a significant amount of cash—perhaps through an inheritance, a work bonus, or the sale of a previous home—and want to lower their monthly overhead without the closing costs associated with refinancing. A common misconception is that a recast shortens the life of the loan; in reality, it keeps the end date the same but provides immediate cash flow relief by reducing the required monthly payment.

Mortgage Recast Calculator Formula and Mathematical Explanation

The math behind a mortgage recast calculator relies on the standard amortization formula. The calculator solves for a new monthly payment (M) using the adjusted principal (P) while holding the interest rate (i) and the remaining number of periods (n) constant.

The Standard Amortization Formula:

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

Variable	Meaning	Unit	Typical Range
P	New Principal Balance (Current Balance – Lump Sum)	USD ($)	$50,000 – $1,000,000+
i	Monthly Interest Rate (Annual Rate / 12 / 100)	Decimal	0.002 – 0.007
n	Remaining Months on Loan	Months	12 – 360
M	New Monthly Principal & Interest Payment	USD ($)	Variable

Practical Examples (Real-World Use Cases)

Example 1: The “New Home Sale” Recast

Imagine a homeowner who bought a new house before selling their old one. They have a $400,000 mortgage at 7% interest with 28 years remaining. After selling their previous home, they have $100,000 in equity. By using the mortgage recast calculator, they find that applying that $100,000 to their current loan drops their monthly payment from approximately $2,725 to $2,044. This saves them $681 every month in cash flow.

Example 2: The Inheritance Recast

A family has a $200,000 balance on a 15-year mortgage at 4.5% with 10 years left. They receive a $50,000 inheritance. Using the mortgage recast calculator, they see their payment drop from $2,071 to $1,553. They choose this over a refinance because current market rates are 7.5%, and recasting allows them to keep their lower 4.5% rate while still reducing their monthly expenses.

How to Use This Mortgage Recast Calculator

1. Enter Current Balance: Check your latest mortgage statement for the remaining principal balance.
2. Input Interest Rate: Enter the annual interest rate of your current loan (e.g., 6.25).
3. Set Remaining Term: Estimate how many years are left until the loan is paid off.
4. Add Lump Sum: Enter the amount you plan to pay toward the principal.
5. Include Fees: Most lenders charge a small administrative fee (often $250-$500) to process a recast.
6. Analyze Results: The mortgage recast calculator will instantly show your new payment and total savings.

Key Factors That Affect Mortgage Recast Results

• Interest Rates: If your current rate is low, recasting is often better than refinancing. If rates have dropped significantly since you got your loan, a refinance might be superior.
• Lump Sum Size: The larger the payment, the more drastic the reduction in your monthly obligation.
• Remaining Time: Recasting earlier in the loan term usually results in more significant interest savings over the life of the loan.
• Lender Participation: Not all lenders offer recasting. FHA and VA loans typically do not allow it, while most conventional loans do.
• Recast Fees: While much lower than refinance closing costs, the fee still impacts your initial “break-even” point.
• Opportunity Cost: Consider if the lump sum could earn a higher return in a high-yield savings account or the stock market compared to your mortgage interest rate.

Frequently Asked Questions (FAQ)

1. Does a mortgage recast lower my interest rate?

No, a mortgage recast calculator shows results based on your existing interest rate. It only changes the principal balance and the monthly payment calculation.

2. How is recasting different from refinancing?

Refinancing involves getting a brand-new loan with new terms and interest rates. Recasting keeps the same loan but re-amortizes the balance after a large payment. Recasting is much cheaper (usually $250-$500) than refinancing ($3,000-$6,000+).

3. Will recasting shorten my loan term?

No. If you have 22 years left on your mortgage, you will still have 22 years left after a recast. To shorten the term, you would simply make extra payments without requesting a recast.

4. Is there a minimum lump sum required for a recast?

Most lenders require a minimum of $5,000 to $10,000, but this varies by institution. Our mortgage recast calculator allows you to test any amount.

5. Can I recast an FHA or VA loan?

Generally, no. FHA and VA loans usually do not support recasting. It is primarily a feature of conventional loans and some jumbo loans.

6. Does recasting affect my credit score?

No, recasting does not involve a credit pull or a new loan application, so it has no impact on your credit score.

7. Can I recast more than once?

Yes, most lenders allow multiple recasts over the life of the loan, provided you meet the minimum payment requirements each time.

8. Should I recast or just pay extra?

If you pay extra without recasting, your monthly payment remains the same, but you pay the loan off faster. If you recast, your monthly payment drops, which improves your monthly debt-to-income ratio and cash flow.

Related Tools and Internal Resources

• Mortgage Refinance Calculator: Compare the cost of a new loan vs. your current one.
• Extra Payment Calculator: See how much time you can shave off your loan by paying extra each month.
• Amortization Schedule Tool: View a month-by-month breakdown of your principal and interest.
• Home Equity Loan Calculator: Explore options for borrowing against your home’s value.
• Debt-to-Income Ratio Calculator: Check how a recast improves your borrowing power.
• Interest Rate Comparison Tool: Track current market trends to see if a recast or refinance is better.