Amortization Recast Savings Calculator

See how a lump sum reshapes your loan. Model recast fees and optional extra payments. Export schedules, compare scenarios, and track long term savings.

Calculator
Enter your remaining balance and term. Add a lump sum and recast fee to estimate payment reduction and interest savings.
Principal still owed today.
Fixed or current rate used for comparison.
Applied immediately, then recast payment.
Add months beyond whole years.
Used to compute net savings and breakeven.
Helpful if you have a non-standard payment.
Used only when selected above.
Adds dates to schedule rows.
Preview size; CSV exports full schedule.
What this compares
  • Current: keep your payment basis over the remaining term.
  • Recast: pay extra principal now, then re-amortize over the same remaining term.
  • Escrow, taxes, insurance, and future rate changes are not included.
Reset
Example data table
Sample inputs and typical outputs for illustration.
BalanceRateTerm leftExtraFeeMonthly reduction
$250,0006.50%25y$20,000$350≈ $130–$170
$180,0005.75%20y$15,000$250≈ $90–$140
$420,0007.00%28y$50,000$500≈ $220–$300
Actual values depend on the exact term, rate, and balance.
Formula used
Core calculations behind the results.
  1. Monthly rate:
    r = (annual_rate ÷ 100) ÷ 12
  2. Monthly payment (principal + interest):
    PMT = B × r × (1+r)n ÷ ((1+r)n − 1)
  3. Monthly interest:
    Interestm = Balancem−1 × r
  4. Monthly principal:
    Principalm = Payment − Interestm

Recast scenario sets new balance = balance − extra principal, then recalculates payment using the same remaining months.
How to use this calculator
A quick workflow for accurate estimates.
  1. Enter your remaining balance, interest rate, and time left.
  2. Add the extra principal amount you plan to pay now.
  3. Enter the lender’s recast fee if applicable.
  4. Use calculated payment, or choose your entered payment.
  5. Click Calculate to see payment reduction and savings.
  6. Export CSV or PDF for sharing and record keeping.

Recast mechanics and payment impact

A recast keeps your interest rate and remaining term unchanged, but recalculates the payment after an immediate principal reduction. For a $250,000 balance at 6.50% with 25 years remaining, a $20,000 lump sum reduces the amortized payment because the new balance is $230,000 across the same 300 months.

Interest savings drivers

Monthly interest is computed as balance × monthly rate, so lowering balance today reduces every future interest charge. The calculator totals remaining interest under the current schedule versus the recast schedule. Larger savings usually come from higher rates, longer remaining terms, and bigger principal reductions. For example, cutting $30,000 from a 7.00% loan with 28 years left can remove thousands in future interest, even if the payment reduction feels modest.

Fee and breakeven interpretation

Many lenders charge a recast fee. This tool reports net savings as interest savings minus the fee, and a simple breakeven months estimate as fee ÷ monthly reduction. If the monthly reduction is $150 and the fee is $450, breakeven is about 3 months. This measure ignores opportunity cost and inflation. If you could earn 5% elsewhere, compare that potential return with the interest you avoid.

Comparing recast to refinancing

A refinance can lower the rate or change term, but may involve appraisal, underwriting, and closing costs. A recast typically has lower paperwork and preserves your existing loan, but it will not change the rate. If your rate is already attractive, a recast can improve cash flow without restarting a long term loan. When rates fall, refinancing may outperform a recast despite higher fees.

Practical data checks before requesting a recast

Use your latest statement for remaining balance, rate, and months left. Confirm whether your payment includes escrow, because this calculator focuses on principal and interest only. Also verify recast eligibility rules, minimum lump sums, and how soon the new payment begins. Export the schedule to document expected balances and payments for budgeting, and keep a copy for lender conversations.

FAQs
Common questions about payment recasts and savings estimates.

1) Does a recast change my interest rate?

No. A recast keeps your current interest rate and remaining term. It only recalculates the required monthly principal and interest payment after a principal reduction, based on the new balance.

2) Will a recast pay off my loan faster?

Not by default. A recast is designed to lower the required payment while keeping the same payoff date. You can still pay extra afterward to shorten the term, but that is optional.

3) Why can interest savings be positive if the term stays the same?

Interest is charged on the outstanding balance each month. When you reduce balance immediately, future interest amounts fall across every remaining month, even though the loan still ends on the same date.

4) What does the breakeven months figure mean?

It estimates how many months of lower payments are needed to recover the recast fee: fee ÷ monthly payment reduction. It is a simple rule of thumb and does not model investment returns or discounting.

5) Should I use “entered payment” or “calculated payment”?

Use calculated payment for standard amortizing loans. Use entered payment if your statement shows a different principal-and-interest payment due to prior adjustments, rounding, or special servicing features.

6) Does this include escrow, taxes, or insurance?

No. The tool models principal and interest only. If your actual payment includes escrow, add those amounts separately when budgeting and when comparing the “before” and “after” total monthly payment.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.