How to decide between fixed-rate and ARM in 5 steps.
Last verified May 23, 2026The direct answer. To decide between fixed and ARM, do five things in order: estimate honestly how long you will stay in the home, compare the rate spread (the ARM's intro rate versus the 30-year fixed), model the worst-case payment after the ARM resets, factor in the friction and cost of refinancing, then decide. The general rule in 2026: choose a 30-year fixed if you plan to stay 7+ years; choose a 5/6 or 7/6 ARM if the spread is 0.75 percentage points or more and you plan to be out within the fixed-rate period. A 1.0-point spread on a $400,000 loan saves about $250 per month in years 1 to 5.
Estimate honestly how long you will stay in the home.
Median US homeownership tenure runs 13 years for single-family homes and 8 years for condos. Plans change. Job moves, family changes, and life events shorten the typical stay. Be honest. A buyer who tells themselves they will stay 15 years but realistically might leave in 5 is the wrong fit for a 30-year fixed and the right fit for a 7/6 ARM.
Compare the rate spread on the same day.
The 30-year fixed rate and the 5/6 or 7/6 ARM rate move together but the spread varies. In May 2026, the typical spread was 0.5 to 1.0 percentage points (ARM lower). A spread under 0.5 points usually does not justify the ARM risk; a spread of 0.75 to 1.5 points is where the ARM math starts to favor short-stay buyers. Get both quotes from the same lender on the same day.
Model the worst-case payment after the ARM resets.
Every ARM has three caps: the initial rate cap (first reset), the periodic rate cap (each subsequent reset), and the lifetime cap (total move from start). A typical 5/6 ARM has 2/2/5 caps: the first reset can move 2 points, each subsequent 6 months 2 points, and the lifetime cap is 5 points above the intro rate. Calculate the payment at the lifetime cap. If you cannot afford the worst case, the ARM is wrong.
Factor in the friction and cost of refinancing.
The standard ARM exit strategy is "refinance before the reset." That assumes rates will be at or below your intro rate when the reset hits. They may not be. Refinance closing costs run 2 to 5 percent of the loan amount. Refinance also requires re-qualifying with current income and credit. A confident refinance plan needs both lower rates and unchanged income at year 5 or year 7.
Decide.
Choose the 30-year fixed if you plan to stay 7+ years, if the spread is under 0.5 points, or if you cannot comfortably afford the lifetime-cap payment. Choose a 5/6 or 7/6 ARM if the spread is 0.75 points or more, if you have a credible exit (sale or refinance) before the reset, and if you can carry the worst-case payment as a backstop. The risk-reward tilts toward fixed for most households in most rate environments.
Five things to verify this week.
- Write down honestly how long you expect to stay in the home.
- Get same-day quotes for the 30-year fixed and a 5/6 or 7/6 ARM from the same lender.
- Use the lender's lifetime cap to calculate the worst-case monthly payment.
- Confirm you could afford the worst-case payment if your refinance plan fails.
- Choose fixed for 7+ years, ARM for shorter with a credible exit and a meaningful spread.
Questions readers ask most often.
What is the difference between a fixed-rate mortgage and an ARM?
A fixed-rate mortgage carries the same interest rate for the entire loan term, typically 15 or 30 years. An adjustable-rate mortgage (ARM) carries a fixed rate for an initial period (3, 5, 7, or 10 years), then adjusts every 6 months based on a market index. The first number in 5/6 ARM is the fixed years; the second is the months between resets after that.
When should I choose an ARM over a fixed-rate mortgage?
Consider an ARM when the rate spread is at least 0.75 percentage points below the 30-year fixed, you have a credible plan to sell or refinance before the fixed period ends, and you can comfortably afford the worst-case payment if the rate hits the lifetime cap. Short-stay buyers (under 7 years) get the most value from a 5/6 or 7/6 ARM.
What are ARM caps?
Every ARM has three caps. The initial cap limits how much the rate can move at the first reset. The periodic cap limits each subsequent reset. The lifetime cap limits the total movement from the starting rate. A 2/2/5 cap structure means 2 points at first reset, 2 points per reset after, 5 points total over the loan life.
Can I refinance an ARM into a fixed-rate mortgage?
Yes, if you qualify at the time of refinance. The standard ARM-to-fixed refinance happens 12 to 18 months before the first reset. You need current income to qualify under the new lender's debt-to-income limits, current credit at or above the prior application, and enough home equity (typically 20 percent or more) to avoid mortgage insurance.
What is a 5/6 ARM versus a 5/1 ARM?
A 5/6 ARM has a 5-year fixed period followed by a rate adjustment every 6 months. A 5/1 ARM has a 5-year fixed period followed by a rate adjustment every 12 months. The 5/6 structure is now the industry standard in 2026 because of the federal regulatory shift away from the LIBOR index to the SOFR index, which resets more frequently.
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Source: True North by Competitive Compass. "How To Decide Between Fixed And Arm In 5 Steps". Published 2026-05-23.
URL: https://competitive-compass.com/true-north/how-to-decide-between-fixed-and-arm-in-5-steps.html