Fixed vs. Adjustable-Rate Mortgages (ARM) Comparison

When shopping for a home mortgage, one of the most critical decisions you'll make is choosing how your interest rate is structured. This choice usually boils down to two options: a **Fixed-Rate Mortgage (FRM)** or an **Adjustable-Rate Mortgage (ARM)**. The option you choose determines your monthly payment stability, the interest you pay over time, and your exposure to market fluctuations. In this guide, we'll compare fixed and adjustable-rate mortgages, explain initial interest rates and adjustment caps, and help you select the right loan type for your situation.

What is a Fixed-Rate Mortgage (FRM)?

A fixed-rate mortgage is a loan where the interest rate remains identical for the entire life of the loan. Whether you choose a 15-year or 30-year term, your interest rate is locked in at closing and will never change. This ensures your monthly principal and interest payment remains stable, regardless of market shifts.

Pros of Fixed-Rate Mortgages:

• Total Predictability: You know exactly what your mortgage payment will be every month, making long-term budgeting straightforward.
• Protection Against Rate Hikes: If interest rates rise across the economy, your rate remains locked, protecting you from payment increases.
• Simplicity: There are no complex formulas, adjustment indexes, or rate caps to understand.

Cons of Fixed-Rate Mortgages:

• Higher Initial Rates: Fixed-rate mortgages typically start with higher interest rates than adjustable-rate mortgages.
• Refinance Required to Lower Rates: If interest rates fall, the only way to lower your monthly payment is to refinance the loan, which requires paying closing costs.

What is an Adjustable-Rate Mortgage (ARM)?

An adjustable-rate mortgage is a loan where the interest rate is fixed for an initial period and then adjusts periodically based on market indexes. ARMs are typically structured as hybrid loans, expressed as two numbers (e.g., 5/1 ARM or 7/6 ARM):

• The First Number (Initial Period): The number of years the interest rate remains fixed. In a 5/1 ARM, the rate is fixed for 5 years. In a 7/6 ARM, the rate is fixed for 7 years.
• The Second Number (Adjustment Period): How often the rate adjusts after the initial period. In a 5/1 ARM, the rate adjusts once a year (1). In a 7/6 ARM, the rate adjusts every six months (6).

How ARM Adjustments and Caps Work

Once the initial fixed period ends, your interest rate adjusts based on a benchmark index (such as the Secured Overnight Financing Rate - SOFR) plus a fixed margin set by your lender. To protect you from extreme market rate hikes, ARMs include **interest rate caps** that limit how much the rate can increase:

1. Initial Adjustment Cap: Limits how much the interest rate can increase the very first time it adjusts after the fixed period ends (typically capped at 2% to 5%).
2. Periodic Adjustment Cap: Limits how much the interest rate can increase from one adjustment period to the next (typically capped at 1% to 2%).
3. Lifetime Cap: The absolute maximum rate increase allowed over the entire life of the loan, regardless of market index heights (typically capped at 5% to 6% above your starting rate).

Pros of Adjustable-Rate Mortgages:

• Lower Initial Payments: ARMs start with lower interest rates than fixed-rate mortgages, making payments more affordable during the initial years.
• Automatic Rate Reductions: If interest rates fall, your monthly payment will decrease automatically without the need to pay for a refinance.
• Ideal for Short-Term Ownership: If you plan to sell the home or refinance before the initial fixed period ends, an ARM saves you money on interest.

Cons of Adjustable-Rate Mortgages:

• Payment Uncertainty: After the initial fixed period, your monthly payment will fluctuate, making long-term budget planning difficult.
• Risk of Payment Shock: If rates rise significantly, your monthly payment could increase by hundreds of dollars.

How to Choose the Right Loan

Choosing between an FRM and an ARM depends on your timeline, financial stability, and market conditions:

• Choose a Fixed-Rate Mortgage if: You plan to stay in the home for a long time (7+ years), value stability, want a predictable monthly budget, and prefer to lock in a low rate during market lows.
• Choose an Adjustable-Rate Mortgage if: You plan to sell the home or refinance within 3 to 7 years, interest rates are currently high and expected to fall, and you want to lock in a lower starting payment.

Conclusion

Both fixed-rate and adjustable-rate mortgages are useful tools when chosen for the right scenario. By evaluating your home ownership timeline and risk tolerance, you can select the mortgage structure that fits your goals. Check our calculators to model your payments today.