A 5/1 ARM has a fixed interest rate for the first 5 years, then adjusts once per year for the remaining 25 years. The initial rate is typically 0.5% to 1% lower than a comparable 30-year fixed rate.

How much can an ARM rate increase?

ARMs have rate caps limiting increases. A common structure is 2/2/5: maximum 2% increase at the first adjustment, 2% per year after, and 5% total increase over the life of the loan. If your starting rate is 5%, the maximum would be 10%.

ARMs carry more risk than fixed-rate loans because your payment can increase substantially after the initial period. However, rate caps limit the maximum increase, and if you plan to sell or refinance before the first adjustment, the risk is minimal.

When should I choose an ARM over a fixed rate?

Consider an ARM if you plan to sell or refinance within 5-7 years, expect interest rates to decrease, or need a lower initial payment to qualify. The initial rate savings can be significant for short-term homeowners.

Fixed vs. ARM: Payment Stability or Lower Initial Rate?

Compare fixed-rate and adjustable-rate mortgages. Understand how ARMs work, when each type makes sense, and the risks and rewards of choosing a lower initial rate.

Fixed-Rate vs. Adjustable-Rate: How They Work

A fixed-rate mortgage keeps the same interest rate for the entire loan term — your payment never changes. An adjustable-rate mortgage (ARM) starts with a lower rate for an initial fixed period, then adjusts periodically based on a market index. The choice comes down to how long you plan to stay and your tolerance for payment uncertainty.

Feature	Fixed-Rate	ARM (e.g., 5/1)
Initial Rate	Higher	Lower (typically 0.5%–1% less)
Rate Changes	Never	After initial period (annually)
Payment Stability	100% predictable	Can increase significantly
Best For	Long-term homeowners	Short-term stays, falling rate markets
Risk Level	Low	Moderate to high
Available Terms	10, 15, 20, 25, 30 years	3/1, 5/1, 7/1, 10/1 ARM

How ARMs Work

Initial Fixed Period

A 5/1 ARM has a fixed rate for 5 years. A 7/1 ARM is fixed for 7 years. During this period, your rate and payment are locked — identical to a fixed-rate mortgage.

Adjustment Period

After the fixed period, the rate adjusts annually (the "1" in 5/1). The new rate = index (like SOFR) + margin (set by lender, typically 2%–3%).

Rate Caps

ARMs have caps limiting how much the rate can change: initial cap (first adjustment), periodic cap (each subsequent adjustment), and lifetime cap (maximum total increase).

Common Cap Structure

A typical 5/1 ARM has 2/2/5 caps: max 2% increase at first adjustment, 2% each year after, and 5% lifetime cap above the initial rate.

When to Choose Fixed-Rate

Fixed Is Better When...

You plan to stay 7+ years — long-term stability outweighs the initial ARM discount
Rates are historically low — lock in a great rate forever
You prefer budget certainty — your payment will never change
You are risk-averse — no surprises, no stress about rate adjustments

When to Choose an ARM

ARM Is Better When...

You plan to sell or refinance within 5–7 years — enjoy the lower rate and move before adjustments
You expect rates to fall — adjustments could actually lower your payment
You need a lower initial payment — ARM savings help you qualify for more home
You can absorb payment increases — strong income with margin for higher payments

The Bottom Line

For most homebuyers, a fixed-rate mortgage is the safer choice. The peace of mind and payment predictability outweigh the initial savings of an ARM. ARMs make sense primarily for buyers who are confident they will sell or refinance within the initial fixed period.

Compare rates: 30-year fixed, 15-year fixed, ARM rates. Use our mortgage calculator to see how different rates affect your payment.