Mortgage Guide

Mortgage basics

Fixed-Rate vs Adjustable-Rate Mortgage

Published by the Mortgage Guide editorial team. Rate assumptions and content updated October 2026. This page is educational. It is not a loan offer, approval, or personalized financial advice.

What is fixed

On a fixed-rate fully amortizing loan, the note rate does not change. Taxes, insurance, and mortgage insurance still can.

The payment calculator assumes the rate you enter stays in place for the whole term.

What can move on an ARM

After the initial period, the rate is typically the index plus a margin, limited by periodic and lifetime caps. This site does not read a live index.

The ARM calculator lets you type a rate to test. If that rate is above the caps, the model uses the cap and says so.

Fixed and adjustable, in brief
LoanRate after closing
FixedStays at the note rate
ARMCan change after the initial period, within caps

Calculators

Related guides

Sources

Common questions

Does the ARM calculator predict my rate?

No. It prices a rate you type, then applies the caps you type.

Are taxes fixed on a fixed-rate loan?

No. Only the note rate is fixed. Escrow bills can change.