Fixed- vs. Adjustable-Rate Mortgage: What's the Difference?

If you're buying a home or refinancing, one of the first choices you'll make is how your interest rate will be structured. As you explore your loan options, you'll likely come across two main types: fixed-rate mortgages and adjustable-rate mortgages (ARMs).

Each loan type works differently, and understanding how they align with your budget and future plans can help guide your decision. Below is a breakdown of how fixed-rate and adjustable-rate mortgages compare to help you decide which option fits your situation.

What Is a Fixed-Rate Mortgage?

A fixed-rate mortgage locks in your interest rate for the entire life of the loan, regardless of what happens in the broader market. As a result, your monthly principal and interest payment stays the same, too, from the first payment to the last.

Fixed-rate loans are available for many major loan types, including conventional loans, FHA loans, VA mortgages and USDA loans.

Common Fixed-Rate Loan Terms

Fixed-rate mortgages typically come in the following term lengths:

• 10-year fixed: Highest monthly payments, but the fastest path to paying off your loan and the least interest paid overall
• 15-year fixed: A middle ground — lower interest paid than a 30-year, with manageable monthly payments
• 20-year fixed: Less common, but useful for borrowers who want a strong mix of cost savings and affordability
• 25-year fixed: A balanced option, providing lower payments than shorter terms with less interest than a 30-year term
• 30-year fixed: The most widely chosen option, offering the lowest monthly payment spread across a longer term

While these are the most common fixed-rate loan terms, Pennymac offers additional flexibility. Depending on the loan type, borrowers may be able to choose customized term lengths anywhere between 10 and 30 years. This can be especially helpful when refinancing and looking to maintain an existing payoff schedule.

Advantages and Potential Drawbacks of a Fixed-Rate Mortgage

Fixed-rate mortgages are a popular choice for homeowners. However, it's important to weigh both the benefits and possible drawbacks to see if a fixed-rate mortgage is the optimal choice for your financial situation.

Advantages:

• Predictable payments make budgeting straightforward
• Protection from rate increases if market rates rise
• Available in multiple loan types (conventional, FHA, VA and USDA)
• Peace of mind knowing your rate won't change

Potential Drawbacks:

• Fixed rates are typically higher than the introductory rate on an ARM
• Less flexibility if market rates drop significantly (though you can refinance at any time)
• May result in paying more interest over time compared to a shorter-term ARM if you move or refinance early

What Is an Adjustable-Rate Mortgage (ARM)?

An adjustable-rate mortgage has two phases. The first is a fixed introductory period — typically 5, 7, or 10 years — during which your rate stays low and stable. After that, the rate can adjust periodically based on a market index, subject to built-in caps that limit how much it can move.

ARMs are available with conventional, FHA and VA loan programs.

Understanding ARM Structure (5/1, 7/1, 10/1, etc.)

The numbers in an ARM label tell you exactly how the loan works:

• The first number: The length of the fixed introductory period (in years)
• The second number: How often the rate adjusts after that period ends

For example:

Conventional ARMs (adjust every 6 months after the fixed period)

• 5/6 ARM: Fixed rate for 5 years, then adjusts every 6 months
• 7/6 ARM: Fixed rate for 7 years, then adjusts every 6 months
• 10/6 ARM: Fixed rate for 10 years, then adjusts every 6 months

Government-backed ARMs (adjust annually after the fixed period)

• 5/1 ARM: Fixed rate for 5 years, then adjusts once per year (commonly used for FHA and VA loans)

ARM Rate Caps

If you're considering an adjustable-rate mortgage, it helps to know there are built-in limits on how much your rate can change. These limits, called rate caps, are designed to prevent sharp increases during the adjustment period.

A typical 5/6 ARM, for instance, may carry caps of 2/1/5. Those numbers mean the rate can increase by no more than 2% at the first adjustment, no more than 1% at each adjustment after that and no more than 5% above the initial rate over the life of the loan.

Government-backed 5/1 ARMs, such as many FHA and VA options, often use caps of 1/1/5, which similarly limit the first adjustment, each future adjustment and the total lifetime increase.

Advantages and Potential Drawbacks of an Adjustable-Rate Mortgage

Adjustable-rate mortgages (ARMs) come with unique benefits and potential challenges that make them a suitable choice for certain borrowers.

Advantages:

• Lower initial rate means lower monthly payments during the introductory period
• A good option if you plan to sell, refinance or pay off the loan before the fixed period ends
• Built-in rate caps limit how high the rate can increase
• If market rates fall after the fixed period, your rate could potentially decrease without refinancing

Potential Drawbacks:

• Once the fixed period ends, monthly payments can increase, depending on market conditions
• Less predictability over the long term compared to a fixed-rate loan
• Requires planning around how long you expect to keep the home

Planning Ahead Before Your ARM Adjusts

As your ARM's introductory period comes to an end, you have options. If you plan to stay in your home long term, refinancing into a conventional fixed-rate mortgage can provide steady, predictable payments for the years ahead. It's a way to lock in stability while continuing to build equity.

Fixed-Rate vs. Adjustable-Rate Mortgage: Key Differences at a Glance

You'll want to choose the mortgage structure that fits your financial goals and homeownership plans. The chart below highlights the main distinctions to help you make an informed decision.

Which Mortgage Option Is Right for You?

The right choice depends on your financial situation, future plans and comfort with payment variability. A few questions worth considering:

• How long do you plan to stay in the home? If you're likely to sell or refinance within 5–7 years, an ARM's lower introductory rate could work in your favor. If you expect to be in your home long term, a fixed rate offers more stability.
• How do you feel about payment variability? Some borrowers find peace of mind in knowing exactly what they'll pay each month. Others are comfortable with some flexibility in exchange for lower initial costs.
• What's your income trajectory? If you expect your income to grow significantly over the next decade, the possibility of higher payments down the road may feel less concerning.
• What's the current rate environment? When rates are relatively low, locking in a fixed rate can be a smart long-term move. When fixed rates are high, an ARM's lower introductory rate may offer meaningful short-term savings.

A fixed-rate mortgage tends to make sense if you:

• Lock in a rate when market conditions are favorable
• Plan to stay in the home for many years
• Value payment consistency above all else

An ARM tends to make sense if you:

• Plan to move, refinance or pay off the loan within the introductory period
• Prefer lower initial monthly payments to free up cash flow
• Expect your income to grow and are comfortable with possible higher payments later

How Interest Rates Can Impact Your Decision

Interest rates influence the overall cost of your mortgage. Even a small difference can affect your monthly payment and the total amount you pay over time.

When rates are low, a fixed-rate mortgage allows you to lock in that rate for the life of the loan. That stability can make long-term planning easier and help protect your payment from market shifts.

For example, on a $300,000 30-year mortgage, the difference between a 6.5% rate and a 6.75% rate could change your monthly principal and interest payment by around $45–$55. Over 30 years, that quarter-point difference can add up to roughly $15,000 in total interest.

An adjustable-rate mortgage (ARM) typically starts with a lower introductory rate, which can mean a lower initial payment. After the fixed period ends, the rate adjusts based on market conditions, which may increase or decrease your payment.

Fixed vs. Adjustable Mortgages for First-Time Homebuyers

For first-time buyers, the fixed-rate mortgage is a widely used choice. Predictable monthly payments make budgeting easier, and there's no need to track rate adjustment schedules or plan for a refinance.

That said, an ARM can be a practical option for first-time buyers who are confident they'll move within the introductory period, or who need lower initial payments to qualify for the home they want.

The best starting point is understanding your options. Both fixed and adjustable mortgages have a place, and neither is inherently better than the other. It all comes down to fit.

Find the Mortgage Structure That Fits Your Plans

Pennymac offers a range of loan programs, including conventional, FHA and VA loans, with both fixed and adjustable-rate structures. Whether you're looking to buy a home or refinance, a Pennymac Loan Expert can walk you through the details, compare scenarios side by side, and help you see how each option may fit your goals and timeline.

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