Recasting Calculator

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Mortgage Recasting Calculator: Lower Your Monthly Payments


Mortgage Recasting Calculator

Curious about mortgage recasting? Use our Mortgage Recasting Calculator to see how a lump-sum payment towards your principal can reduce your monthly mortgage payments without changing your loan term or interest rate. Input your current loan details and lump sum to estimate your new payment and potential interest savings.

Recast Your Mortgage


Your outstanding loan principal before the lump-sum payment.


Your current annual mortgage interest rate.


The number of years left on your mortgage before the recast.


The extra amount you’ll pay towards the principal.


Fee charged by some lenders to recast a mortgage (typically $0 – $500).



What is Mortgage Recasting?

Mortgage recasting, sometimes called loan re-amortization, is a process where your lender recalculates your monthly mortgage payment after you make a significant lump-sum payment towards your principal balance. Unlike refinancing, recasting a mortgage does not change your interest rate or the loan’s maturity date (the end date of your loan term). Instead, it adjusts your amortization schedule based on the new, lower balance, resulting in lower monthly payments for the remainder of your existing loan term.

The primary goal of using a Mortgage Recasting Calculator is to see how much your monthly payment would decrease. This can be beneficial if you’ve come into some extra money (like an inheritance, bonus, or sale of an asset) and want to reduce your monthly housing expenses without the costs and hassle of a full refinance. A recasting calculator helps you quantify this benefit.

Who Should Consider Recasting?

  • Homeowners with a large sum of cash they want to put towards their mortgage.
  • Those who want lower monthly payments but already have a favorable interest rate and don’t want to refinance.
  • Borrowers who want to keep their current loan term and avoid extending it, as often happens with refinancing.
  • People whose lenders offer recasting (not all do, and it’s more common with conventional loans than FHA or VA loans).

Common Misconceptions

  • Recasting vs. Refinancing: They are different. Refinancing involves getting a new loan, often with a different rate and term, and paying off the old one. Recasting modifies the payment of your existing loan.
  • Term Shortening: Recasting does NOT shorten your loan term. The end date remains the same. If you simply make a large extra payment without recasting, your term shortens, but your required payment stays the same.
  • Interest Rate Change: Recasting does not change your current interest rate.

Mortgage Recasting Formula and Mathematical Explanation

The core of a Mortgage Recasting Calculator lies in the standard loan payment formula (M) based on the principal (P), monthly interest rate (i), and number of payments (n):

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

When you recast, you make a lump-sum payment, which reduces the principal ‘P’. The term ‘n’ (number of remaining payments) and the interest rate ‘i’ stay the same.

Before Recasting:

  1. Pold = Current Loan Balance
  2. i = Annual Interest Rate / 12
  3. n = Remaining Loan Term in Months
  4. Mold = Pold [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]

After Recasting:

  1. Pnew = Current Loan Balance – Lump Sum Payment
  2. i = Annual Interest Rate / 12 (same)
  3. n = Remaining Loan Term in Months (same)
  4. Mnew = Pnew [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]

The recasting calculator shows you Mnew and the total interest saved over the remaining term.

Variables Table

Variable Meaning Unit Typical Range in Calculator
Current Loan Balance The amount you currently owe before the lump sum. $ 50,000 – 2,000,000+
Annual Interest Rate The yearly interest rate on your mortgage. % 2 – 10+
Remaining Loan Term Years left on your mortgage. Years 1 – 30
Lump-Sum Payment Extra payment towards principal. $ 5,000 – 500,000+
Recasting Fee Lender’s fee for the service. $ 0 – 500
Monthly Payment Amount paid each month. $ Calculated

Practical Examples (Real-World Use Cases)

Example 1: Lowering Monthly Expenses

Sarah has a $300,000 mortgage balance with 25 years remaining at a 6% interest rate. Her current monthly payment (P&I) is $1,932.90. She receives a $50,000 inheritance and decides to use it to recast her mortgage. Her lender charges a $250 fee.

  • Current Balance: $300,000
  • Interest Rate: 6%
  • Remaining Term: 25 years
  • Lump Sum: $50,000
  • Recast Fee: $250

After recasting, her new balance is $250,000. Her new monthly payment for the remaining 25 years would be $1,610.75. This frees up $322.15 per month in her budget, and she saves over $46,000 in interest over the life of the loan compared to if she hadn’t made the lump sum and recast (even more compared to just making the lump sum without recasting and paying off early).

Example 2: Managing Windfall

John has a $400,000 balance with 18 years left at 5.5%. His payment is $2,866.45. He gets a $100,000 bonus. He wants to reduce his payments rather than shorten the term. His lender offers recasting for free.

  • Current Balance: $400,000
  • Interest Rate: 5.5%
  • Remaining Term: 18 years
  • Lump Sum: $100,000
  • Recast Fee: $0

After recasting, his new balance is $300,000. His new monthly payment for the remaining 18 years becomes $2,149.84, a saving of $716.61 per month. Using a Mortgage Recasting Calculator helped him see the immediate cash flow benefit.

How to Use This Mortgage Recasting Calculator

  1. Enter Current Loan Balance: Input the amount you currently owe on your mortgage.
  2. Enter Annual Interest Rate: Provide your current mortgage interest rate as a percentage.
  3. Enter Remaining Loan Term: Input the number of years left until your mortgage is paid off.
  4. Enter Lump-Sum Payment Amount: Specify the extra amount you plan to pay towards your principal before recasting.
  5. Enter Recasting Fee: If your lender charges a fee for recasting, enter it here (otherwise, leave as 0 or the default).
  6. Calculate and Review: The recasting calculator will automatically update, showing your new lower monthly payment, interest savings, and a comparison table.

Reading the Results

The calculator displays:

  • New Monthly Payment: Your reduced principal and interest payment after recasting.
  • Old Monthly Payment: Your payment before recasting.
  • New Loan Balance: Your balance after the lump sum.
  • Interest Saved: The estimated total interest you’ll save over the remaining term due to recasting.
  • Comparison Table & Chart: A breakdown of old vs. new payments, total interest, and total paid.

Use these results to decide if the reduction in monthly payment and interest savings are worth the lump-sum payment and any recasting fee, especially compared to other uses of the money or just making extra payments without recasting.

Key Factors That Affect Mortgage Recasting Results

  • Lump-Sum Amount: The larger the lump-sum payment, the lower your new balance and thus the lower your new monthly payment and greater interest savings.
  • Interest Rate: While recasting doesn’t change your rate, a higher existing rate means a larger portion of your original payment was interest, so reducing the principal can have a more significant impact on the interest portion of the new payment.
  • Remaining Loan Term: The longer the remaining term, the more payments are affected, and the more total interest savings can be realized over time, although the per-payment reduction might seem smaller compared to a shorter term with the same lump sum.
  • Recasting Fees: A high fee might reduce the net benefit, especially with smaller lump sums. Our Mortgage Recasting Calculator includes this.
  • Lender Policies: Not all lenders offer recasting, or they may have minimum lump-sum requirements or limit how often you can recast. Check with your lender first. Consider the terms of your mortgage.
  • Loan Type: Recasting is more common with conventional loans. Government-backed loans (FHA, VA) may have different rules or not allow it.
  • Financial Goals: If your goal is lower monthly payments, recasting is good. If it’s to pay off the loan faster, just making extra payments without recasting achieves that, though the required payment remains the same until it’s paid off. Explore different mortgage strategies.

Frequently Asked Questions (FAQ)

What is the main benefit of recasting a mortgage?
The primary benefit is a lower required monthly mortgage payment without changing your interest rate or loan term, improving your monthly cash flow.
Does mortgage recasting affect my credit score?
No, recasting your mortgage does not typically affect your credit score as it’s not a new loan application or credit inquiry, just an adjustment to your existing loan’s amortization schedule.
Is it better to recast my mortgage or just make extra payments?
If you want to lower your required monthly payment, recast. If you want to pay off your loan faster but keep the same payment until it’s done, make extra payments without recasting. Our recasting calculator helps compare.
How much does it cost to recast a mortgage?
It varies by lender. Some offer it for free, while others charge a fee, typically between $100 and $500. Our calculator includes a fee input.
Can I recast any type of mortgage?
Not always. It’s most common with conventional loans. FHA and VA loans have stricter rules and may not allow it easily. Check with your lender or servicer.
How large does my lump-sum payment need to be to recast?
Lenders may have minimums, often $5,000 or $10,000, or a certain percentage of the balance. Check your lender’s policy.
Will recasting change my loan’s end date?
No, the original maturity date of your loan remains the same when you recast.
How long does the recasting process take?
It usually takes 30-60 days after you make the lump-sum payment and request the recast from your lender.
Is recasting the same as refinancing?
No. Refinancing replaces your old loan with a new one, usually with a new rate and term. Recasting adjusts the payment on your existing loan with the same rate and end date.

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