Recast the existing loan
A lump-sum principal payment reduces the balance. Your servicer recalculates principal-and-interest payments over the original remaining term at the same fixed rate, if the loan qualifies.
Free advanced browser calculator
Mortgage Recast Calculator
Estimate your new monthly payment after a large principal payment. Compare a mortgage recast against keeping your old payment—and see how each choice changes lifetime interest and payoff timing.
Customize your scenario
Start with the realistic example or enter your own numbers. Calculations run on this device.
Power of Interest — free calculator report
Your estimated results
Illustrative numbers based on your assumptions. Updated when you calculate.
New recast monthly P&I—Principal & interest only
Monthly payment reduction—Versus the original payment
Interest saved by recasting—Before the recast fee
Principal after lump payment—
Current estimated P&I—
Interest savings less fee—
Three mortgage outcomes
Each outcome starts today from your current balance; the lump sum applies immediately before the first modeled payment.
| Scenario | Monthly P&I | Interest remaining | Payoff date |
|---|---|---|---|
| No lump payment | — | — | Original term |
| Lump sum + recast | See above | — | — |
| Lump sum + keep payment | Current P&I | — | — |
Months saved if you keep paying more—
Recast interest + administrative fee—
Interest with lump sum / old payment—
Refinance comparison
Assumes refinancing only the balance after your principal payment, not withdrawing cash.
New refinance P&I—
Refinance interest—
Interest + closing costs—
Recast interest + fee minus refinance interest + costs: —. This is not a present-value calculation; compare terms and fees before deciding.
Remaining mortgage balance over time
Complete amortization schedule
| # | Month | Payment | Principal | Interest | Balance |
|---|
Estimates only—not a lender payoff quote, credit offer, or financial advice. Taxes, insurance, escrow and lender-specific payment rules are not modeled.
How to decide whether to recast your mortgage
Pay principal, keep your payment
Rather than reducing the payment, continue making the previous amount. You may reduce total remaining interest more and finish paying sooner.
Consider refinancing
Refinancing means a new loan with a potentially different rate, remaining term, closing costs and qualification requirements. Compare full costs—not just the monthly bill.
Mortgage recast calculator FAQs
What is a mortgage recast?
A mortgage recast (re-amortization) is a new monthly principal-and-interest calculation after a qualifying lump-sum principal reduction. Typically, the rate and remaining maturity do not change. You must confirm your loan and servicer are eligible.
Does a recast save more interest than paying extra without recasting?
Often no. Because a recast lowers the required payment, keeping your original payment after the same lump sum will usually pay off the mortgage faster and reduce remaining interest more. A recast primarily frees up monthly cash flow.
Do I have to refinance to lower my payment?
Not necessarily. A permitted recast can reduce the monthly principal-and-interest obligation without a new mortgage. Rules, minimum curtailments, fees, and timing vary by loan and servicer.
Are property tax, homeowners insurance and escrow included?
No. All payments shown are principal and interest. A recast normally does not directly lower the escrow portion of your mortgage payment. The tool uses monthly accruals and assumes the principal reduction is applied just before the next modeled payment.
How accurate are the payments?
They are mathematical estimates for a fixed-rate, fully amortizing mortgage with the number of remaining months entered. Lender rounding and payment timing may differ. Verify the actual loan balance, interest rate, eligibility, payoff date, fee, and effective month with your servicer.
Reference: Fannie Mae's explanation of a re-amortized mortgage.
Need editable loan schedules?
Explore Amortization Pro →Go beyond a one-time estimate with Amortization Pro
Build, edit, print, save and revisit complete amortization schedules in our Windows software.
Also try the HELOC Payment Calculator, Mortgage Payoff CalculatorMortgage Recast CalculatorHELOC Payment CalculatorMortgage Recast CalculatorHELOC Payment CalculatorMortgage Recast CalculatorHELOC Payment Calculator or Refinance Calculator.