Fixed vs Adjustable Rate Mortgage: 2026 Comparison

I Almost Locked In the Wrong Rate

Last spring I was sitting across from a loan officer, staring at two term sheets for a rental property I'd been eyeing — a duplex listed at 285,000. One sheet said 6.75% fixed for 30 years. The other said 5.9% adjustable, 5/1 ARM, with caps I didn't fully understand at the time. The monthly difference was about 180 bucks, which on a cash-flowing duplex is the difference between a decent deal and a great one. I nodded like I understood the ARM terms. I didn't.

So I went home and spent the next two weeks running every scenario I could think of, and honestly, that process changed how I look at mortgage selection entirely. If you're evaluating a property right now — maybe this week — here's what I wish someone had laid out for me in plain language.

The Numbers Side by Side (2026 Projections)

Before we get into the weeds, here's a comparison table I put together based on where rates are sitting as of early 2026. These are ballpark figures — your lender's numbers will vary — but they're realistic enough to do real math with.

Feature	30-Year Fixed	5/1 ARM	7/1 ARM
Starting Rate (approx.)	6.50% – 6.85%	5.75% – 6.10%	6.00% – 6.30%
Monthly Payment (250k loan)	~1,580 – 1,640	~1,460 – 1,520	~1,500 – 1,550
Rate Adjustment Period	Never	Every year after year 5	Every year after year 7
Typical Rate Cap (per adjustment)	N/A	2% per year	2% per year
Lifetime Cap	N/A	5% over initial	5% over initial
Best For	Long-term holds, stability	Flips, short-term holds	Medium-term investors

That monthly difference might look small, but run it out over 60 months and you're talking about 7,200 to 10,800 in saved cash flow during the fixed period of an ARM. That's real money — enough to cover a roof repair or fund your next down payment.

But here's the catch.

After that initial period ends, your ARM rate resets. And if rates have climbed (or even just stayed flat at today's levels), your payment could jump by 300 or 400 a month practically overnight. I've seen investors get squeezed hard by this, especially on properties where the rent growth didn't keep pace with the rate adjustment. So the savings aren't free — they come with a bet attached.

How I Actually Decide Between Fixed and Adjustable

This is the part that took me the longest to figure out, and it's honestly less about the rate itself and more about your strategy for the property. Let me walk through how I think about it now.

Question one: How long am I holding this thing? If I'm buying a rental I plan to keep for 15+ years, I almost always go fixed. The predictability is worth more than the savings. I can model my

with confidence because that payment isn't going anywhere. My cap rate calculation stays stable, my cash-on-cash return stays stable, and I sleep fine.

But if I'm looking at a BRRRR deal — buy, rehab, rent, refinance, repeat — and I plan to refinance within 2-3 years anyway? An ARM makes a ton of sense. Why pay for 30 years of rate certainty when you're only using 24 months of it?

Question two: What's my margin of safety? I run the numbers assuming the ARM hits its worst-case scenario. If the property still cash flows (even barely) at the lifetime cap rate, I'm comfortable. If it goes negative, I either need a bigger down payment or I should go fixed.

For that duplex I mentioned — the one at 285,000 with a 250,000 loan — the worst-case ARM payment at 10.9% would've been roughly 2,370 a month. The property was renting for 2,800 total (both units combined). So even in the absolute worst scenario, I'd still be slightly positive after taxes and insurance, though basically breaking even. That was tight enough that I ended up going fixed.

Question three: Can I refinance if I need to? This is the escape hatch everyone mentions but nobody stress-tests. Refinancing costs money — usually 2% to 3% of the loan balance, so on a 250k loan you're looking at 5,000 to 7,500 in closing costs. And refinancing assumes rates will be lower when you need them to be, which is an assumption, not a guarantee. I've watched people plan their entire investment thesis around a future refi that never made financial sense when the time came.

Use a

to model both scenarios. Seriously — plug in the fixed rate, then plug in the ARM rate and manually adjust it upward year by year. See where the crossover point is. For most 2026 rate spreads, the ARM saves you money for about 7-9 years before the fixed starts winning (assuming moderate rate increases of 0.5% per adjustment).

A Few Things People Get Wrong

"ARMs are risky" is something I hear constantly, and it's.. partially true? An ARM on your primary residence where you have no exit strategy and a tight budget — yeah, that's risky. An ARM on an investment property you're planning to sell in 3 years with 25% equity? That's just math.

The risk isn't in the product. It's in the mismatch between the product and your plan.

Another thing — people forget that the spread between fixed and adjustable rates changes constantly. In 2023, the gap was tiny (sometimes under 0.5%), so ARMs barely made sense. Right now in 2026, we're seeing spreads of 0.5% to 0.75% on average, which starts to pencil out for shorter holds. Check the

to see how even small rate differences compound over time.

And one more: the index your ARM is tied to matters. Most ARMs these days are pegged to SOFR (Secured Overnight Financing Rate), which replaced LIBOR. Ask your lender what index they use and what the margin is — that margin (usually 2.5% to 3%) gets added to the index rate at each adjustment. If you don't know the margin, you can't model the worst case, and if you can't model the worst case, you're guessing.

Run your

both ways. Check your

under each scenario. And if you're comparing properties, use a

to see which deal actually performs better after financing costs.

FAQ

Can I switch from an ARM to a fixed rate later?

Yes — it's called refinancing, and it's pretty common. But it's not free. You'll pay closing costs (typically 2-3% of the loan), and you'll need to qualify again based on your credit, income, and the property's appraised value at that time. Some lenders offer "convertible ARMs" that let you switch to fixed without a full refi, but the conversion rates are usually not great. Don't count on refinancing as a sure thing — treat it as a backup plan, not your primary strategy.

Which is better for a rental property I plan to hold for 10 years?

Fixed. Almost always. A 7/1 ARM might work if you're confident about refinancing around year 6, but for a decade-long hold, the payment predictability of a fixed rate makes your cash flow projections way more reliable. And reliable projections mean better decisions about whether to buy the next property.

How much can an ARM rate actually increase?

It depends on the cap structure, but a common setup is 2/2/5 — meaning 2% max increase at first adjustment, 2% max at each subsequent adjustment, and 5% max over the life of the loan. So a 5.9% starting rate could theoretically reach 10.9%. That's the number you need to stress-test against.

— and I mean literally the day you're sitting in that loan officer's chair — the right choice comes down to your hold period, your risk tolerance, and whether you've actually run the worst-case numbers. I've used both types on different properties, and neither one is inherently better. The mistake is picking one without doing the math first. So do the math. Use a

to make sure your property qualifies either way, and go from there.