Recast Calculator
Calculate your new monthly mortgage payment and total interest savings after a principal recast.
New Monthly Payment
Based on standard amortization formula
Payment Comparison
| Comparison Metric | Before Recast | After Recast |
|---|
What is a Recast Calculator?
A Recast Calculator is a specialized financial tool designed to help homeowners understand the impact of a mortgage recast. Unlike refinancing, which involves getting a completely new loan with a new interest rate, a mortgage recast keeps your existing loan and interest rate intact. Instead, you make a significant lump sum payment toward your principal balance, and the lender re-calculates (re-amortizes) your monthly payments based on the new, lower balance.
Who should use a Recast Calculator? This tool is ideal for individuals who have come into a windfall of cash—such as an inheritance, a work bonus, or proceeds from a home sale—and want to lower their monthly financial obligations without the high closing costs associated with refinancing. A common misconception is that a recast shortens the loan term; in reality, it only reduces the monthly payment while keeping the original payoff date the same.
Recast Calculator Formula and Mathematical Explanation
The mathematical logic behind the Recast Calculator relies on the standard fixed-rate amortization formula. The goal is to solve for the monthly payment (P) given the new principal balance (L), the monthly interest rate (c), and the remaining number of months (n).
The Formula:
P = L [c(1 + c)^n] / [(1 + c)^n – 1]
Step-by-step derivation:
- Step 1: Determine the new principal balance by subtracting your lump sum payment from the current balance.
- Step 2: Convert the annual interest rate into a monthly decimal (Annual Rate / 12 / 100).
- Step 3: Identify the remaining months left on the original mortgage term.
- Step 4: Apply the amortization formula to find the new monthly installment.
Variables Table
| Variable | Meaning | Unit | Typical Range |
|---|---|---|---|
| L (Principal) | Remaining loan balance after lump sum | USD ($) | $50,000 – $1,000,000 |
| c (Rate) | Monthly interest rate (Annual / 12) | Decimal | 0.002 – 0.007 |
| n (Term) | Remaining months in the loan | Months | 12 – 360 |
| P (Payment) | The resulting monthly payment | USD ($) | Varies |
Practical Examples (Real-World Use Cases)
Example 1: The Inheritance Windfall
Imagine a homeowner with a Recast Calculator scenario where they owe $300,000 at a 4% interest rate with 20 years (240 months) remaining. Their current payment is $1,817.94. They receive a $50,000 inheritance and decide to recast. By entering these values into the Recast Calculator, they see their new balance is $250,000. The new monthly payment drops to $1,514.95, providing a monthly savings of $302.99.
Example 2: The "Buy Before You Sell" Strategy
A family buys a new home before selling their old one. They take out a large mortgage initially. Once their old home sells, they have $100,000 in equity. They use the Recast Calculator to see the impact on their $500,000 loan at 6% interest with 30 years remaining. The recast reduces their payment from $2,997.75 to $2,398.20, significantly improving their monthly cash flow.
How to Use This Recast Calculator
Using our Recast Calculator is straightforward and requires only a few pieces of information from your latest mortgage statement:
- Enter Principal: Input the current amount you owe, not the original loan amount.
- Input Rate: Use your current fixed interest rate.
- Remaining Months: Count how many months are left until your loan is fully paid off.
- Lump Sum: Enter the amount you plan to pay toward the principal.
- Fees: Include the lender's recast fee to see the true net benefit.
Once entered, the Recast Calculator instantly updates the results. Focus on the "Monthly Savings" to see how much extra cash you will have each month for other investments or expenses.
Key Factors That Affect Recast Calculator Results
- Lump Sum Size: The larger the payment, the more dramatic the reduction in your monthly bill.
- Remaining Term: Recasting early in a 30-year mortgage has a different impact than recasting with only 5 years left.
- Interest Rate: While the rate doesn't change, a higher rate means a larger portion of your original payment was interest, making the principal reduction more effective at lowering the total cost.
- Lender Participation: Not all lenders offer recasting. FHA and VA loans typically do not allow it, while most conventional loans do.
- Recast Fees: While usually small ($200-$500), these fees are a "sunk cost" that should be factored into your break-even analysis.
- Timing of Payment: Making the lump sum payment immediately before the recast processing date ensures the math aligns with your expectations.
Frequently Asked Questions (FAQ)
No, the Recast Calculator assumes your interest rate remains exactly the same. If you want a lower rate, you would need to refinance.
It depends. Recasting is cheaper (lower fees) and doesn't require a credit check or appraisal, but it won't lower your interest rate. Refinancing is better if market rates have dropped significantly.
Generally, no. FHA and VA loans do not typically support recasting. It is most common with conventional and jumbo loans.
You can use the calculator as often as you like! However, most lenders only allow one actual recast every 12 months or a limited number of times over the life of the loan.
No. The Recast Calculator shows that your payoff date remains the same. Only the monthly payment amount changes.
Most lenders require at least $5,000 to $10,000 to perform a recast, though this varies by institution.
No, a recast only affects the principal and interest portion of your payment. Your escrow items (taxes and insurance) remain the same.
Usually, no. Since you aren't getting a new loan, lenders typically do not require a new home appraisal.
Related Tools and Internal Resources
- Mortgage Payoff Calculator – See how much time you can shave off your loan with extra monthly payments.
- Amortization Schedule – View a month-by-month breakdown of your principal and interest.
- Refinance Calculator – Compare the costs of a new loan versus a simple recast.
- Extra Payment Calculator – Calculate interest savings without re-amortizing your loan.
- Loan Comparison Tool – Compare different loan terms and interest rates side-by-side.
- Principal Reduction Guide – Learn the best strategies for paying down your mortgage debt faster.