Fixed-Rate vs ARM: Which Actually Saves You More?

The conventional wisdom says fixed is safe and ARMs are risky. The real answer is more nuanced. The right choice depends on exactly one thing: how long you plan to keep the loan.

When a fixed rate wins

If you stay in your home for 10+ years, a 30-year fixed is almost certainly cheaper. You lock in a rate today and never worry about adjustments. No surprises, no stress.

The math: A 6.75% fixed rate costs more upfront than a 6.00% 7/1 ARM, but from year 8 onward, the fixed costs less than the ARM would after its first adjustment.

When an ARM wins

If you move or refinance within the fixed period, an ARM saves you money.

Example: You take a 7/1 ARM at 6.00% instead of a fixed at 6.75%. You keep the house for 6 years and sell. Your total interest saved: about $12,000-$15,000 on a $400k loan.

The break-even game

The ARM saves you money every month during the fixed period. It potentially costs more after adjustment. The question is: will the cumulative savings exceed the potential extra cost?

• Move in 5 years? ARM almost always wins.
• Stay 10+ years? The fixed usually wins.
• Stay 7-8 years? It's a coin flip — and the ARM savings may still come out ahead.

What about refinancing?

If rates drop, you can refinance either loan. But with an ARM, you might not need to — if rates drop, your ARM might adjust lower too. With a fixed, you'd need to refi to capture the savings.

The real risk

The risk isn't the ARM itself. It's buying a house you can barely afford with an ARM, then getting stuck when rates rise. If you have a comfortable payment buffer and a realistic timeline, that risk drops to near zero.

The takeaway: "Fixed is always better" is a rule of thumb, not a rule. Run the numbers on your actual timeline. If you're moving in 7 years, the ARM probably saves you thousands.