Fixed vs Variable Rate Mortgage

Our Verdict: Fixed rate offers certainty and is best when rates are low. Variable (ARM) offers lower initial rates and is best when you plan to move or refinance within 5-7 years.

Fixed Rate Mortgage

Variable Rate (ARM)

In-Depth Analysis

Fixed vs. variable mortgage is fundamentally a bet on the future direction of interest rates — and a question of how well you can absorb payment uncertainty. Fixed-rate mortgages guarantee a locked rate for the full loan term, typically 15 or 30 years. Adjustable-rate mortgages (ARMs) offer a lower initial rate for a fixed period (commonly 5, 7, or 10 years) before adjusting annually based on a benchmark index (typically SOFR or the 1-year Treasury) plus a margin. Neither is universally better; the right choice depends on your time horizon, risk tolerance, and the current interest rate environment.

The initial rate advantage of ARMs can be significant. In most rate environments, a 7/1 ARM (fixed for 7 years, then adjusting annually) carries an interest rate 0.5–1.5% lower than a 30-year fixed mortgage. On a $400,000 loan, that 1% difference equals approximately $250/month in savings during the initial fixed period — or about $21,000 over 7 years before any adjustment. For borrowers who are confident they'll sell or refinance within the ARM's fixed period, this represents pure savings with essentially no interest rate risk taken.

The risk of an ARM is precisely defined by its caps and index. Well-structured ARMs have three caps: an initial cap (maximum rate increase at first adjustment, typically 2%), a periodic cap (maximum change per subsequent adjustment, typically 2%), and a lifetime cap (maximum increase above the start rate over the life of the loan, typically 5%). A 7/1 ARM at 5.5% with 2/2/5 caps could rise to no more than 10.5% — ever. Understanding these specific caps (not just the initial rate) is essential to evaluating an ARM's worst-case scenario. Rate caps were the consumer protection widely absent in the pre-2008 subprime ARM market.

The decision framework: time horizon first, rate environment second. If you'll stay in the home definitely longer than the ARM's fixed period, the fixed rate is almost certainly the safer choice — you eliminate payment uncertainty during the period most exposed to rate changes. If you'll sell within 5–7 years with high confidence, the ARM's initial savings are nearly risk-free (you'll sell before the adjustable period begins). In high-rate environments, ARMs are more attractive because fixed rates are expensive and rates are more likely to fall than rise over the following decade. In low-rate environments, locking in the historically low fixed rate is usually optimal.