Recast Loan Calculator
Calculate your new monthly savings after a mortgage re-amortization.
$1,519.14
$1,688.13
$168.99
$225,000.00
$25,697.00
Monthly Payment Comparison
Visualizing the reduction in your monthly mortgage obligation.
| Metric | Before Recast | After Recast | Difference |
|---|
Formula: New Payment = [r * (P – L)] / [1 – (1 + r)^-n], where r is monthly interest, P is balance, L is lump sum, and n is remaining months.
What is a Recast Loan Calculator?
A recast loan calculator is a specialized financial tool designed to help homeowners understand the impact of a mortgage re-amortization. Unlike refinancing, where you replace your current loan with a new one (often changing the interest rate and term), a mortgage recast involves keeping your existing loan but recalculating the monthly payments after a significant lump-sum principal payment.
Homeowners typically use a recast loan calculator when they have sudden access to capital—such as an inheritance, a work bonus, or proceeds from selling a previous home—and want to lower their monthly overhead without the closing costs associated with refinancing. By using a recast loan calculator, you can instantly see how much your “burn rate” decreases, freeing up monthly cash flow for other investments or living expenses.
One common misconception is that recasting reduces the interest rate. It does not. The primary benefit shown by a recast loan calculator is the reduction in required monthly principal and interest payments, while maintaining your original loan term and interest rate.
Recast Loan Calculator Formula and Mathematical Explanation
The math behind a recast loan calculator relies on the standard amortization formula, but it is applied to the adjusted principal balance. The goal is to solve for the new payment (P) that will retire the new balance over the remaining months (n) at the current interest rate (i).
The core formula used is:
Variables Table
| Variable | Meaning | Unit | Typical Range |
|---|---|---|---|
| PV_new | Remaining Balance minus Lump Sum | USD ($) | $50,000 – $1,000,000 |
| r | Monthly Interest Rate (Annual Rate / 12) | Decimal | 0.002 – 0.007 (2% – 8%) |
| n | Remaining Number of Months | Months | 60 – 360 months |
Practical Examples (Real-World Use Cases)
To better understand how a recast loan calculator functions, let’s look at two scenarios where a borrower might choose to re-amortize.
Example 1: The New Home Move
A family buys a new home before selling their old one. They take out a $500,000 mortgage at 6%. Once their old home sells, they have $100,000 in equity. By using a recast loan calculator, they find that applying this $100,000 to their current $500,000 balance reduces their monthly payment from approximately $2,997 to $2,398. This $599 monthly saving significantly improves their debt-to-income ratio.
Example 2: The Annual Bonus
A professional with a $300,000 balance at 5.5% and 20 years remaining receives a $30,000 bonus. They use the recast loan calculator to determine that while a simple principal payment would shorten their loan term, a recast will instead lower their payment by roughly $206 every month for the next 20 years, providing more flexibility in their monthly budget.
How to Use This Recast Loan Calculator
- Enter Current Balance: Check your latest mortgage statement for the remaining principal balance.
- Input Interest Rate: Use your current fixed annual interest rate.
- Set Remaining Term: Estimate how many years are left on your loan. If you have 22 years and 4 months left, enter 22.3.
- Input Lump Sum: Enter the amount you plan to pay toward the principal. Note that most banks require at least $5,000 to $10,000 to initiate a recast.
- Analyze Results: The recast loan calculator will immediately show your new payment and the total monthly savings.
Key Factors That Affect Recast Loan Calculator Results
- Lump Sum Size: The larger the payment, the more dramatic the payment reduction. Small payments rarely justify the administrative fees.
- Current Interest Rate: While recasting doesn’t change the rate, the math of a recast loan calculator shows that higher-rate loans see a greater reduction in payment per dollar applied.
- Remaining Term: If you only have 5 years left, the payment drop will be much sharper than if you have 25 years left.
- Bank Fees: Most lenders charge a fee (typically $250 – $500) to process a recast. Factor this into your recast loan calculator considerations.
- Loan Type: FHA and VA loans generally do not allow for recasting, while most conventional and jumbo loans do.
- Inflation: Reducing a monthly payment today might be more valuable than paying off a loan early if inflation is high and you have a low fixed rate.
Related Tools and Internal Resources
- Mortgage Refinance Calculator – Compare recasting vs. getting a brand new loan.
- Principal Only Payment Calculator – See how extra payments shorten your loan term.
- Debt-to-Income Ratio Tool – Check how a recast improves your borrowing power.
- Amortization Schedule Generator – View month-by-month breakdowns of your mortgage.
- Investment vs Mortgage Payoff Calculator – Decide if recasting is better than the stock market.
- Extra Payment Savings Calculator – Calculate total interest saved by paying more early.
Frequently Asked Questions (FAQ)
Refinancing replaces your loan with a new one at market rates. Recasting keeps your current rate and term but lowers the payment by applying a lump sum to the principal. A recast loan calculator helps you see the latter.
No. Your interest rate remains exactly what it was before the recast process began.
No. One thing a recast loan calculator clearly shows is that the end date of your mortgage stays the same; only the monthly amount due changes.
Generally, no. FHA and VA loans typically do not offer recasting as an option. You would need to use a mortgage refinance calculator for those loan types.
Most lenders require a minimum of $5,000 or $10,000, though this varies by servicer. Check with your bank before using the recast loan calculator.
Lenders usually charge a flat administrative fee between $150 and $500. This is much cheaper than refinance closing costs.
No, recasting is a purely administrative change to your existing account and does not involve a new credit pull or new debt account.
If your rate is below 3-4%, you might earn more by investing that lump sum elsewhere. Use a recast loan calculator to see the savings, then compare it to potential investment returns.