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Mortgage Recast Calculator

New monthly payment after a lump-sum principal reduction.

Compute your new monthly mortgage payment after a one-time lump-sum principal reduction (a "recast"). Reports the old payment, new payment, monthly savings, and total interest saved over the remaining term.

Nadia Almasri By Nadia Almasri
Published Last reviewed 1 min read

Inputs

$
%
$

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

New balance = current_balance − lump_sum. New payment = new_balance · r / (1 − (1 + r)^−n), where r = APR/1200 and n is remaining months.

In depth

Compute your new monthly mortgage payment after a one-time lump-sum principal reduction (a "recast"). Reports the old payment, new payment, monthly savings, and total interest saved over the remaining term.