WebToolArcDo nothing
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- Payoff
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- Remaining interest
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- Cash used now
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Home / Finance Calculators / Mortgage Recast Calculator
Finance Calculators
Mortgage Recast Calculator
See the new required payment after a lump-sum principal reduction, compare recast versus keeping the old payment, include the servicer fee, and reverse-solve a target payment.
Recast planning workspace
Lower the payment — or keep paying and finish sooner
Model the same lump-sum principal payment three ways: no change, recast to a lower required payment, or keep the old payment to accelerate payoff.
Your current loan
Enter the five numbers your servicer can confirm
Use the unpaid principal balance, note rate, and remaining term from your statement. Enter your servicer's actual recast fee if known.
What changes after the same lump sum?
Recast after lump sum
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- Payoff
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- Remaining interest
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- Cash used now
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Lump sum + keep old payment
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- Payoff
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- Remaining interest
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- Cash used now
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The recast path keeps the same modeled maturity. The prepay path uses the same lump sum but continues the old modeled P&I, so it generally pays off earlier instead of lowering the required payment.
How much lump sum gets you to a target payment?
—Required principal reduction
Year-by-year balance comparison
| Elapsed | Do nothing balance | Recast balance | Keep old payment balance | Do nothing interest | Recast interest | Keep old payment interest |
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Method, eligibility & what to confirm with your servicer
What this calculator models
- A fixed-rate mortgage with standard monthly principal-and-interest amortization.
- The lump sum is applied fully to principal before the recast or keep-paying comparison.
- A recast keeps the entered rate and remaining term, then recalculates P&I on the lower balance.
- The prepay comparison keeps the old modeled P&I and therefore can finish earlier.
What you should verify
- Your servicer must permit the recast and may set a minimum principal curtailment, fee, timing rule, or loan-type restriction.
- Taxes, insurance, mortgage insurance, HOA, escrow and any lender-specific posting rules are excluded.
- Recast fees do not change the new principal balance; this tool treats the entered fee as cash paid separately.
- This is a planning estimate, not a servicer quote or financial, tax, legal, or lending advice.
Core borrowing, saving & investing workflows
Start with the broad calculator that matches the decision, then move to a specialist only when the loan structure, cash flow, tax treatment, debt strategy or savings goal genuinely changes.
Mortgage CalculatorHome payment, taxes, PMI & payoffLoan CalculatorFixed payment, interest & feesCompound InterestCompounding & recurring contributionsSavings CalculatorDeposits, APY & goalsAuto LoanVehicle price, tax & financingAmortizationPayment schedule & total interestRetirementContributions, inflation & incomeInvestmentReturns, fees & target growth
What makes a recast different from a normal extra payment?
A principal curtailment lowers what you owe immediately. A recast goes one step further: if your servicer approves it, the remaining balance is re-amortized using the current interest rate and remaining term so the required principal-and-interest payment falls. If you instead keep paying the old amount after the same lump sum, you typically finish earlier and pay less interest, but you do not get the same required-payment relief.
Why compare the fee and the keep-paying path?
The recast fee is usually small relative to a mortgage balance, but it is still part of the payment-relief decision. The fee-payback metric shows how many months of required-payment reduction equal the entered fee. The keep-paying scenario makes the trade-off explicit: lower required payment versus faster payoff.
Confirm the actual rules before sending a lump sum
Servicer eligibility, minimum principal reductions, fees, timing and loan-type rules vary. Use your servicer's quoted terms and verify that the principal curtailment and recast will be processed the way you expect.