basic

ARM Mortgage Calculator

Initial vs. fully-indexed payment on an adjustable-rate mortgage.

Compare the initial fixed-rate payment on a 5/1, 7/1, or 10/1 ARM with the worst-case fully-indexed payment after the first reset, given the index, margin, and rate cap.

Nadia Almasri By Nadia Almasri
Published Last reviewed 1 min read

Inputs

$
yr
%
%
%
%

Results

Enter values and click Calculate to see results.
Was this helpful?

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

Worst-case rate after reset = min(initial + first_cap, index + margin). Payment is recomputed on the remaining term with the new rate.

In depth

Compare the initial fixed-rate payment on a 5/1, 7/1, or 10/1 ARM with the worst-case fully-indexed payment after the first reset, given the index, margin, and rate cap.