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Mortgage Calculators

Mortgage Recast Calculator

See how a lump-sum payment plus a recast lowers your monthly mortgage payment without changing your rate or term.

Recast keeps your original rate and term; only the remaining balance is re-amortized after the lump sum.

$
%
yr
$
$
New monthly payment
$1,688/mo
Down from $2,026/mo — same rate, same payoff date.
Monthly savings
$338/mo
New balance
$250,000
Interest saved (net of fee)
$51,031
Explain this result

Turn the numbers above into plain-language takeaways. Educational only — not financial advice.

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Overview

How the Mortgage Recast Calculator Works

A recast is the quiet alternative to refinancing. You make a large lump-sum payment against principal, and the lender re-amortizes the remaining balance over your remaining term — same rate, same payoff date, lower monthly payment. It usually costs a few hundred dollars instead of thousands in closing costs, which makes it the better move when your rate is already good and you have come into cash.

Formula

The Math Behind the Calculator

New Balance = Current Balance − Lump Sum. New Payment = New Balance × r / (1 − (1 + r)^−n), where r is the unchanged monthly rate and n is the months remaining on the original term. Interest Saved = (Original remaining interest) − (Interest on the recast schedule) − Recast Fee.

Example

A Worked Example

You owe $320,000 at 4.25% with 24 years left, paying $1,915 a month. You apply a $50,000 lump sum and pay a $300 recast fee. The balance drops to $270,000, and re-amortized over the same 24 years the payment falls to $1,616 — $299 less each month — while you save roughly $36,000 in interest and keep your 4.25% rate untouched. Refinancing to achieve the same payment would mean giving up that rate and paying several thousand in closing costs.

How to use

How to Use the Mortgage Recast Calculator

  1. 1Enter your current principal balance from your latest statement, not the original loan amount.
  2. 2Enter your current interest rate and the number of years remaining on the loan.
  3. 3Enter the lump sum you intend to apply to principal.
  4. 4Add the recast fee your servicer charges, typically $150–$500.
  5. 5Compare the result against simply making the lump-sum payment without a recast, which shortens the term instead of cutting the payment.
Interpretation

What the Results Mean

  • The new monthly payment is permanently lower, with no change to your interest rate.
  • Interest saved comes from the smaller balance accruing interest for the rest of the term.
  • The payoff date stays the same as before, which is the key difference from making extra payments without recasting.
  • If the payment reduction is small relative to the lump sum, your remaining term is short and the cash may work harder elsewhere.
Keep exploring

Smart Next Steps

What to explore next
Avoid

Common Mistakes to Avoid

  • Assuming every loan qualifies — FHA, VA, and USDA loans generally cannot be recast, and jumbo rules vary by servicer.
  • Recasting when a refinance would be better, which is usually the case if current market rates are well below your rate.
  • Emptying an emergency fund into the lump sum; recast money is locked in home equity and hard to retrieve.
  • Not confirming that the servicer will apply the payment to principal and process a recast, rather than treating it as prepaid installments.
  • Overlooking that the same lump sum without a recast would eliminate years from the loan instead of lowering the payment.
Scope

Limitations of This Calculator

  • It does not check eligibility. Most servicers require a minimum lump sum, often $5,000–$10,000, and government-backed loans typically do not allow recasting at all.
  • Taxes, insurance, PMI, and HOA are excluded, so the payment shown is principal and interest only.
  • It does not compare against investing the lump sum instead, which may produce a higher return than the mortgage rate.
  • Only one recast is modeled; some servicers allow one over the life of the loan.
  • PMI removal is not modeled even though a large lump sum may push you below 80% loan-to-value.
Keep going

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FAQ

Frequently Asked Questions

What is the difference between a recast and a refinance?+

A recast keeps your existing loan, rate, and term and only re-amortizes a smaller balance, costing a few hundred dollars. A refinance replaces the loan entirely with new terms and full closing costs.

Which loans can be recast?+

Most conventional conforming loans can, subject to servicer rules. FHA, VA, and USDA loans generally cannot. Always confirm with your servicer before making the lump-sum payment.

How much does a recast cost?+

Typically a flat $150–$500 administrative fee, versus 2–5% of the loan amount for a refinance.

Should I recast or just make extra payments?+

Extra payments without a recast shorten the term and save more interest overall. A recast lowers the required monthly payment, which is better if cash flow flexibility matters more to you.

Does recasting change my interest rate?+

No. That is the main appeal — you keep a low legacy rate while reducing the payment, something a refinance in a higher-rate market cannot do.

Financial Disclaimer

This calculator is for educational and estimation purposes only. It does not provide financial, mortgage, tax, investment, or legal advice. Actual rates, payments, taxes, fees, insurance costs, eligibility, and loan terms vary by lender, location, credit profile, and market conditions. Always compare official offers and consult a qualified professional before making financial decisions.

Last updated June 2026 · Prepared by the mCalculator Editorial Team