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Mortgage Recast Calculator

See what happens when you apply a lump sum to principal and then re-amortize the loan. Keeps the same rate and payoff date, but lowers your monthly payment. Compared here against simply prepaying the same amount without recasting.

Your numbers

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%
yrs
mo

How far into the loan you are today

$

Leave at 0 to calculate from the schedule

$
$

Most servicers charge $150 to $500

After the recast

New monthly payment$2,200
Old monthly payment$2,528
Monthly savings$328

Same rate of 6.5%, same remaining term of 27 years, re-amortized over a lower balance.

Loan snapshot

Current balance (before lump sum)$385,669
Balance after lump sum$335,669
Remaining term27 years

Break-even on the recast fee

Months to recover the fee2 mo

At $328 per month of savings, the $350 fee pays for itself in about 2 months.

Recast vs Prepay-Only

Two ways to use the same $50,000 lump sum. Recast lowers the payment but keeps the original payoff. Prepay-only keeps the payment and shortens the loan.

Recast
$2,200/mo
Payoff in 27 years
Interest over remaining life: $377,291
Prepay-only
$2,528/mo
Paid off in 19 years 8 months (7 years 4 months early)
Interest over remaining life: $258,688

Prepay-only saves about $118,604 more in interest, but the monthly payment stays the same. Recast is for monthly cash flow, prepay-only is for a faster payoff.

Interest over the remaining life

Do nothing$433,491
Recast (with lump sum)$377,291
Prepay-only (same lump sum)$258,688
Interest saved by recast vs no action$56,200
Results are estimates based on user inputs and do not represent loan terms, APR, or a financing offer. Pre-filled values are illustrative examples, not available or quoted rates. Actual terms depend on credit, property, program, and underwriting. Every result applies to the entered planning scenario, not an observation period or local market statistic. Replace price, tax, insurance and fee allowances with dated, property-specific figures. Missing inputs are not assumed to be zero.

Not sure whether to recast, prepay, or refinance?

Work through cost comparisons and a fillable quote sheet with the free Refinance Decision Guide. No email or signup required.

Download free guide (PDF)

Want a plain-English walkthrough? Refinance vs recast decision guide.

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15 vs 30 Year Comparison

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Frequently asked questions

What is a mortgage recast?
A recast applies a lump-sum principal payment and recalculates the payment over the remaining loan term at the existing rate. It does not replace the mortgage with a new loan.
How is a recast different from refinancing?
A recast keeps the existing loan and rate while recalculating payments after a principal reduction. A refinance pays off the old loan with a new one, which can change the rate, term, and closing costs.
Can every mortgage be recast?
No. Eligibility, minimum principal payment, fees, and servicing rules vary by loan and servicer. Ask your servicer whether your loan can be recast and what requirements apply.

Related glossary terms

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Related reading

Want the story behind the numbers?

  • HubWhen to refinanceWhen a recast beats a full refinance.Read
  • ArticleWhat actually moves mortgage rates (and what does not)Context on whether today's rate justifies a refi instead.Read
    Try: Refinance
  • HubRate-and-term refinanceThe alternative path if a recast doesn't pencil.Read
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Amortization Calculator

See exactly how each payment splits between principal and interest, with a full month-by-month schedule.

Use amortization calculator

Prepayment Calculator

Mix lump sum, extra monthly, and biweekly payments. See how many months and how much interest you save.

Calculate payment

15 vs 30 Year Comparison

Compare a 15-year and a 30-year mortgage side by side. See the monthly difference and lifetime interest.

Use 15 vs 30 year comparison calculator

Points & Rate Buydown Calculator

Model discount points or a temporary 2-1 / 3-2-1 buydown. Break-even, monthly savings, and total subsidy.

Use points & rate buydown calculator