Fixed vs. Adjustable-Rate Mortgages
Choosing between a fixed rate and an adjustable rate is really a choice about certainty versus flexibility. Here is how each works and how to tell which fits your plans.
Fixed-Rate Mortgages
A fixed-rate mortgage locks your interest rate for the entire life of the loan — most commonly 15 or 30 years. Your principal-and-interest payment never changes, no matter what happens to the broader economy. This predictability makes budgeting simple and protects you completely from rising rates.
The trade-off is that fixed rates usually start higher than the introductory rate on an adjustable loan, and if market rates fall you must refinance (and pay closing costs) to benefit. For most buyers who plan to stay put, the peace of mind is well worth it.
Adjustable-Rate Mortgages (ARMs)
An ARM starts with a fixed introductory rate for a set period, then adjusts periodically based on a market index. You will see them written as 5/1, 7/1, or 10/1: the first number is the years the initial rate is locked, and the second is how often it adjusts afterward (here, once per year).
The introductory rate is typically lower than a comparable fixed rate, which means smaller early payments. After the intro period, the rate can rise or fall. Reputable ARMs include caps — limits on how much the rate can change per adjustment and over the life of the loan — so always read the cap structure (often shown as something like 2/2/5) before signing.
A Side-by-Side Comparison
Fixed-Rate
- Payment never changes
- Full protection from rate increases
- Simple to budget long-term
- Higher starting rate
- Must refinance to lower your rate
Adjustable-Rate
- Lower introductory rate and payment
- Can benefit if rates fall
- Payment uncertainty after intro period
- Exposed to rate increases (within caps)
- More complex terms to understand
Which One Is Right for You?
Choose fixed if you plan to stay in the home long-term, value predictable payments, or are buying when rates are relatively low and you want to lock them in.
Consider an ARM if you expect to move or refinance before the intro period ends, want lower initial payments, or believe rates are likely to fall — and you can comfortably afford the payment if they rise instead.
Stress-test the worst case. Before choosing an ARM, calculate your payment at the maximum possible rate under its caps. If that number would strain your budget, the lower intro rate is not worth the risk.
Use the calculator to model both options: run a fixed rate, then run the ARM's intro rate and its worst-case capped rate as separate saved scenarios and compare them side-by-side.
Run Your Numbers with Mortgage Walk
Put these ideas to work. Use the free Mortgage Walk calculator to estimate your monthly payment, visualize your amortization schedule, and compare multiple scenarios side-by-side — no sign-up required.
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