Finance

Mortgage Recast Calculator

Find your new lower monthly payment after a lump-sum principal payment and mortgage recast.


Mortgage Recast Calculator

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A recast keeps your rate and term exactly as they are — only the balance drops after a lump sum, and the lender recalculates a lower payment against it.

How it works

The lump sum reduces the remaining balance. The new, lower balance is re-amortized over the same remaining term at the same rate, producing a lower monthly payment without changing the loan’s payoff date.

What this does not include

This doesn’t include the lender’s recast fee (often $150-$500, a flat charge unrelated to the payment math) — a real, if usually modest, cost of using a recast.

How to use this calculator

  1. Enter your remaining balance, lump-sum payment, interest rate, and remaining term.

A worked example

A $250,000 remaining balance, $50,000 lump-sum payment, 6% rate, 300 months remaining: old payment = $1,610.75, new payment after recast = $1,288.60, monthly savings = $322.15.

What the variables mean

Variable Meaning
Remaining balance Mortgage balance before the lump sum
Lump sum Extra payment applied toward principal
Rate Current interest rate
Remaining months Months left on the loan term

Edge cases worth knowing

Recasting lowers the monthly payment without changing the interest rate or term — unlike refinancing, which can change both. It simply re-amortizes the same loan over the same remaining time using the smaller balance.

A lump sum that exceeds the remaining balance is impossible — the calculator declines to show a result for that case, since it would mean paying off more than what’s owed.

Frequently asked questions

How is recast different from refinancing?

Refinancing replaces the loan entirely with a new rate, term, and closing costs; recasting keeps the same loan and rate, simply lowering the payment against a smaller balance for a small flat fee.

Does recasting shorten my loan term?

No — the payoff date stays the same; only the monthly payment drops, unlike making extra payments toward an early payoff, which shortens the term instead.

Do all lenders and loan types allow recasting?

No — recasting availability depends on the lender and loan type; many conventional loans allow it, but some loan types (including many FHA and VA loans) generally do not.

Important: This is general information, not financial advice. Figures are estimates, and your lender or provider decides the real numbers. Check with a qualified adviser before acting on them.

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Written by

M. Whitfield

Personal finance writer

M. Whitfield writes the personal finance calculators, covering loans, mortgages, savings, tax and investment maths. The focus is on showing exactly which number goes into a formula and which assumptions a result depends on, so readers can tell when a figure applies to their situation and when it does not. Every finance page states what it does not account for as plainly as what it does.

Reviewed by

A. Whitfield-Reyes

Calculator reviewer — finance

A. Whitfield-Reyes reviews the finance calculators, checking compounding conventions, rate-period alignment, and whether each page is explicit about the costs and tax treatment it leaves out. Financial results are easy to state with false precision, so review focuses on whether the page makes its assumptions visible to a reader who is not looking for them.

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