Mortgage Recast Calculator — Calculate Lump-Sum Monthly Savings

Calculate lower monthly payments and interest savings after a lump-sum recast.

Quick Answer

A mortgage recast re-amortizes your remaining loan balance after a lump-sum principal reduction while keeping your original interest rate and loan term unchanged.

Last updated: 2026-07-31 Editorially reviewed by PakDigitalz Editorial Team

Free mortgage recast calculator. Estimate how much a lump-sum principal payment reduces your monthly mortgage payment and lifetime interest.

Mortgage Recast Calculator

Determine how much a lump-sum principal payment lowers your monthly mortgage payment. A mortgage recast re-amortizes your remaining loan balance at your existing interest rate without the cost or hassle of refinancing.

Recast Loan Parameters

Recast Impact Summary

Rate Kept: 6.5%

Previous Monthly P&I

$2,025.62

New Recast Monthly P&I

$1,688.02

Monthly Payment Reduction

$337.6

New Recast Payment: $1,688.02/mo

New Loan Balance

$250,000

Lifetime Interest Saved

$51,281.07

Net Benefit (After Fee)

$51,031.07

Why Choose Recasting Over Refinancing?

Recasting requires no home appraisal, no income verification, and no closing costs. You keep your low existing interest rate while immediately lowering your required monthly payment.

How a Mortgage Recast Works

When you receive a windfall—such as an inheritance, annual bonus, tax refund, or proceeds from selling another property—you can apply a large lump-sum payment directly to your mortgage principal. A mortgage recast takes your lower principal balance and re-amortizes it over the exact number of months remaining on your loan.

Mortgage Recast vs. Refinance

Mortgage Recast

  • • Retains your current interest rate
  • • Retains your remaining loan term
  • • Small administrative fee ($250–$500)
  • • No credit check or appraisal required

Mortgage Refinance

  • • Replaces your rate with current market rates
  • • Resets your loan term (e.g. back to 30 years)
  • • Standard closing costs (2% to 5% of loan)
  • • Full credit approval & appraisal required

Compare your options using our full suite of home loan tools: visit the primary Mortgage Calculator or check your break-even point with the Refinance Calculator.

Frequently Asked Questions About Mortgage Recasting

What is a mortgage recast?

A mortgage recast (or loan re-amortization) occurs when you make a large lump-sum principal payment toward your existing mortgage balance. Your lender recalculates your monthly principal and interest payment based on the lower balance while keeping your original interest rate and remaining loan term identical.

How does a mortgage recast differ from a mortgage refinance?

Recasting keeps your existing loan, current interest rate, and original loan maturity date; it simply recalculates lower monthly payments for a small lender fee ($250 to $500). Refinancing replaces your entire mortgage with a new loan, requiring a full credit check, home appraisal, and standard closing costs (typically 2% to 5% of the loan amount).

Do all mortgages qualify for a recast?

Most conventional conforming Fannie Mae and Freddie Mac loans permit recasting. FHA, VA, and USDA government-backed loans generally do not allow recasting. Contact your mortgage servicer to verify eligibility and minimum lump-sum requirements (typically $5,000 to $10,000).

Does recasting shorten my mortgage loan payoff period?

No. Recasting lowers your required monthly payment amount while keeping your original loan payoff date unchanged. If you wish to shorten your loan payoff timeline instead of lowering monthly payments, keep making your original monthly payment after submitting the lump sum.

How to Use This Tool

  1. Enter your current mortgage balance, remaining loan term (years), and existing interest rate.
  2. Enter the lump-sum principal reduction payment you plan to make.
  3. Include your lender's administrative recast fee (typically $250 to $500).
  4. Compare your previous monthly payment with your lower recast payment and total lifetime interest saved.

Formula & Specifications

New Principal Balance = Current Balance - Lump Sum Payment
Monthly Payment = (Balance * Rate * (1 + Rate)^n) / ((1 + Rate)^n - 1)
Monthly Savings = Old Monthly Payment - New Monthly Payment
Net Lifetime Savings = Total Old Interest - Total New Interest - Recast Fee

About Mortgage Recast Calculator

Free mortgage recast calculator. Estimate how much a lump-sum principal payment reduces your monthly mortgage payment and lifetime interest.

Frequently Asked Questions

What is a mortgage recast?

A mortgage recast re-amortizes your lower remaining loan balance after a lump-sum principal payment without changing your interest rate or term.

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Expert Note

This tool uses the latest international formulas and rates. Results are for estimation purposes. For legal or financial decisions, consult a qualified professional. Built and maintained by the PakDigitalz team.

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