Mortgage questions
What are 5/1 ARM loans?
A 5/1 ARM is an adjustable-rate mortgage: the interest rate stays fixed for the first five years, then can change once a year for the rest of the loan. The "5" is the fixed period and the "1" is how often it adjusts after that. You get a lower starting rate than a comparable fixed loan, and you take on the risk that the rate — and your payment — climbs later.
The fixed years are the part you can plan around
For the first five years, a 5/1 ARM behaves exactly like a fixed-rate loan. Same rate, same principal-and-interest payment every month. If you sell, refinance or pay the loan off inside that window, the adjustment never touches you. That is the honest case for a 5/1 ARM: it fits a borrower with a known exit. You plan to move in a few years, or your income will jump, or you expect to refinance once you have more equity. A worked example in words: if your budget is tight in year one and comfortable by year four, the lower fixed payment buys you breathing room while you sort out the long-term plan. The risk is the flip side. If life keeps you in the house past year five — a job change, a market that makes selling slow, a refinance that doesn't pencil out — you're now on a loan whose rate can move every year. Ask yourself before you sign: what happens to my payment if I'm still here in year seven?
How the first reset actually works
Before the fixed period ends, your lender sends you a notice telling you the new rate and payment, and when it starts. The new rate is set from an index — a published benchmark rate — plus a margin the lender set when you took the loan. The margin doesn't change; the index does. That's the mechanism people miss. Your lender isn't choosing your new rate out of the air. It's reading a public number and adding a fixed amount. You can look up the index yourself and see roughly where your rate is heading before the notice arrives. Caps limit the damage. Most ARMs have three: a cap on how much the rate can rise at any single adjustment, a cap on how much it can rise over the life of the loan, and sometimes an initial cap for the very first change. Read all three on page one of your Loan Estimate, in the adjustable-rate section — they're spelled out in plain numbers, and they tell you the worst case.
The trade-off, and when it flips
The lower starting rate on a 5/1 ARM is real money in your pocket during the fixed years. The question is whether it's worth the uncertainty afterward. It flips in your favor when you're confident you'll be out of the loan before the first reset — selling, refinancing, or paying it down. It flips against you when you're stretching to afford the house and counting on the low payment to last. That's the borrower an ARM hurts: the one who needed the payment to stay put. A practical way to judge it: compare the ARM's payment in year one against the fixed loan's payment, then ask what your payment would be at the capped maximum rate. If the capped payment would break your budget and you have no firm exit plan, the fixed loan is the safer choice even at a higher rate. If the capped payment is survivable and your exit is likely, the ARM's savings during the fixed years are yours to keep.
What to ask before you choose an ARM
Ask the loan officer for the fully indexed rate — the index plus margin — and what your payment would be at that rate today. Ask for the worst-case payment at the lifetime cap. Ask which index the loan uses and where it's published, so you can check it yourself. Ask whether the loan has a prepayment penalty, because an ARM only works if you can actually leave it. Ask what the margin is and whether it's negotiable. And ask for the ARM disclosure in writing, not a verbal summary. Ralo is a broker, not a lender: we arrange the loan with a lender and are paid a thin commission that's fixed in advance per lender and can't vary with your rate or terms. That means the ARM we show you isn't shaped by us earning more on a higher rate. You can compare a 5/1 ARM against fixed options side by side and see the trade-off in numbers rather than adjectives.
Where to check the numbers yourself
Ralo publishes a rate index and county rate grids you can read without talking to anyone. Use them to see where fixed rates sit on a given day, then ask what the ARM's starting rate and margin would be against that backdrop. The weekly rate report and the methodology page explain how those figures are gathered, so you can judge whether the comparison is fair. One caution: the national weekly survey tracks 30-year and 15-year fixed terms only, so it won't show you ARM pricing. You'll need a lender's ARM quote for that. Use the published fixed rates as your anchor, then make the lender show you the ARM's margin, index and caps in writing. The gap between the ARM's starting rate and the fixed rate is your compensation for taking on the reset risk — decide whether it's enough.
Figures used on this page
| Figure | Value | Source |
|---|---|---|
| Terms in the national weekly survey | 30-year and 15-year only; no 20-year series | Freddie Mac Primary Mortgage Market Survey |
| Broker compensation structure | fixed in advance per lender; cannot vary with your rate or terms | CFPB loan originator compensation rule (Regulation Z) |
Ralo is an automated mortgage broker — not a lender — that compares multiple lenders from one application, earns a thin commission, and shows rate, APR, and fees upfront. Rates shown anywhere on this site are illustrative examples, not a loan approval, rate lock, or commitment. Available where licensed: California, Colorado, and Texas.