5/1 ARM Explained

Introduction

A 5/1 ARM (adjustable-rate mortgage) has an interest rate that stays fixed for the first 5 years, then can adjust once per year. The "5" is the initial fixed period in years; the "1" is how often the rate can adjust after that (annually). A 5/1 ARM often starts with a lower rate than a 30-year fixed, which can reduce your mortgage payment during the first 5 years. After that, the rate moves with an index plus a margin, subject to caps.

See What Is an Adjustable Rate Mortgage, Fixed vs Adjustable Rate Mortgage, and ARM vs Fixed-Rate Calculator.

How a 5/1 ARM Works

For the first 5 years, your interest rate and mortgage payment (principal and interest) are fixed. After year 5, the rate adjusts annually based on an index (such as SOFR or a Treasury index) plus a margin. If the index rises, your rate and payment can increase—up to the periodic cap (e.g., 2% per year). A lifetime cap (e.g., 5% above the initial rate) limits the total increase over the loan.

Under TRID (TILA-RESPA Integrated Disclosure), your Loan Estimate shows the initial rate, index, margin, adjustment schedule, and caps. The APR is based on the initial rate and may not reflect future adjustments.

5/1 ARM vs 7/1 and 10/1 ARMs

A 7/1 ARM is fixed for 7 years, then adjusts annually. A 10/1 ARM is fixed for 10 years. Longer fixed periods mean more payment certainty but often a slightly higher initial rate. The 5/1 typically has the lowest initial rate among common ARMs—and the earliest adjustment. Choose based on how long you expect to keep the loan.

When a 5/1 ARM May Make Sense

• Planning to sell or refinance in 5 years or less: You benefit from the lower initial rate without facing an adjustment.
• Expecting a large income increase: You may be able to absorb a higher payment after year 5.
• Rates are high and you expect them to fall: You could refinance to fixed before or after the first adjustment.

A 5/1 ARM may not make sense if you plan to stay 10+ years and want payment certainty. A fixed-rate mortgage avoids adjustment risk.

Frequently Asked Questions

What does 5/1 ARM mean?

The first number (5) is the initial fixed period in years—your rate stays the same for 5 years. The second number (1) means the rate can adjust once per year after that. So a 5/1 ARM is fixed for 5 years, then adjusts annually.

What happens after the first 5 years?

After 5 years, your rate adjusts based on an index (e.g., SOFR) plus a margin. It can go up or down, subject to rate caps. Your mortgage payment will change with each adjustment. The Loan Estimate shows the adjustment schedule and caps.

What are 5/1 ARM rate caps?

ARMs typically have a periodic cap (e.g., 2% per adjustment) and a lifetime cap (e.g., 5% above the initial rate). These limit how much your rate and payment can increase. The Loan Estimate under TRID shows your specific caps.

When does a 5/1 ARM make sense?

A 5/1 ARM can make sense if you plan to sell or refinance within 5 years—you benefit from the lower initial rate without facing an adjustment. It may not make sense if you plan to stay long-term and want payment certainty. See Fixed vs Adjustable Rate Mortgage.

Is the 5/1 ARM initial rate always lower than fixed?

Often yes, but not always. Market conditions vary. Compare the APR, mortgage payment, and total cost over your expected ownership period using the Loan Estimate.

Sources

• Consumer Financial Protection Bureau (CFPB) – Adjustable-rate mortgages
• Federal Housing Finance Agency – ARM disclosures