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ARM VS FIXED CALCULATOR

ARM vs Fixed Calculator

Compare an adjustable-rate mortgage against a fixed-rate loan over your planned hold period — see total P&I cost both ways and a recommendation based on the gap.

Loan basics
84 mo

Default 84 = 7 years. Slider snaps in 1-year increments.

Fixed-rate option
ARM option

Initial fixed period = 5 years; rate then adjusts annually.

Typically 0.25–1.0% lower than fixed

Forecast: where the index sits when the ARM resets

Added to index for new rate (set at origination)

Max change per adjustment (after the first)

Max ever above initial rate

ARM saves over your hold
$8,645
Lean ARM

Over your hold period and assumptions, the ARM saves money. Re-check that the index-at-adjustment assumption is conservative — that is the line the comparison turns on.

Fixed scenario
Monthly P&I
$2,661.21
Total P&I over 7 years
$223,542
ARM scenario
Initial monthly P&I
$2,462.87
Adjusted rate (capped)
7.500%
Adjusted monthly P&I
$2,796.86
Months at initial rate
60
Months at adjusted rate
24
Total P&I over 7 years
$214,897

Enter your contact info to download the PDF summary.

Estimate only. Simplified model: a single rate adjustment at the end of the initial fixed period, capped at the lifetime cap. Real ARMs adjust annually thereafter and the periodic cap also limits per-adjustment changes — modeling the full schedule requires a month-by-month simulation. Total cost uses monthly P&I × months and ignores principal-payoff timing differences between scenarios.
How to read this comparison

ARM vs Fixed — match the loan to the hold.

The ARM vs fixed decision is not really a question about interest rates — it is a question about how long you will actually be in the loan. ARMs trade rate certainty for an initial-period discount; the trade is a winner if your honest hold horizon is shorter than the initial fixed period, and it is a loser if you stay longer and rates have risen.

What is an ARM?

An adjustable-rate mortgage is a loan whose interest rate is fixed for an initial period — typically 5, 7, or 10 years — and then adjusts annually based on a market index (today most commonly SOFR, the Secured Overnight Financing Rate) plus a margin set at origination. The shorthand "5/1" means 5 years fixed, then adjusts every 1 year. "7/1" is 7 fixed-then-annual; "10/1" is 10 fixed-then-annual. During the initial fixed period, the rate is typically 0.25–1.00% lower than a comparable 30-year fixed. After that, the payment can rise — or fall — with the market.

How ARM rate caps work

ARMs do not let the rate move freely — they come with three caps that limit volatility. The initial cap (often equal to the lifetime cap) limits the very first adjustment. The periodic cap (typically 2%) limits every subsequent annual adjustment. The lifetime cap (typically 5–6% above the initial rate) is the absolute ceiling — your rate can never exceed initial-rate + lifetime-cap, regardless of where the index goes. The cap structure is your downside-protection mechanism: even in a worst-case rate-shock scenario, you know exactly how high the rate can go before you sign.

When ARM beats fixed (short hold)

The math is simple: if you sell or refinance before the ARM adjusts, you captured the entire initial-rate discount with zero downside. A military move at year 4, a job relocation at year 5, a planned trade-up at year 6 — these are textbook ARM scenarios. The slider above lets you see the break-even visually: at short holds, the ARM total cost is dramatically lower than fixed; at longer holds, the adjusted rate eats the discount and may overtake the fixed loan entirely.

When fixed beats ARM (long hold or rising rates)

If you plan to be in the home for 15+ years and rates rise materially, the fixed-rate loan wins on cumulative interest and on payment certainty. Even if the ARM math models out slightly in favor of the ARM, the value of knowing your payment for 30 years has a real psychological premium that most borrowers (correctly) pay for. The fixed-rate loan also eliminates the refinance-or-eat-the-adjustment decision point at year 5/7/10 — one less thing to manage.

Texas ARM market context

ARM volume in Texas has tracked national averages — when the rate gap between ARM and fixed is small (under 25 bps) ARM share drops to single-digit percent of originations; when the gap widens (50–100 bps) ARM share moves into the 15–20% range. As of 2026, with fixed rates in the high-6s to low-7s and ARM initial rates in the low-to-mid 6s, the decision is meaningfully back on the table for the right borrower. The right borrower in Texas is typically a relocation buyer with a sub-7-year horizon, a high-DTI buyer using the ARM payment to qualify with a refi plan, or an investor matching loan term to a planned exit.

ARM glossary

Quick reference

Index
Market rate the ARM tracks. Today: typically SOFR (Secured Overnight Financing Rate).
Margin
Fixed amount added to the index. Set at origination, never changes.
Initial cap
Max increase at the first adjustment. Often equal to the lifetime cap.
Periodic cap
Max change per annual adjustment after the first. Typically 2%.
Lifetime cap
Absolute ceiling above the initial rate. Typically 5–6%.
FAQ

Common ARM-vs-fixed questions.

Picking between ARM and fixed? Call us at (903) 402-5626 — we will quote both and walk through the trade-offs.

Should I get a 5/1, 7/1, or 10/1 ARM?
Match the initial fixed period to your honest expected hold. If you are confident you will sell or refinance in 4–5 years (military move, job change pending, school district transition), a 5/1 ARM gives you the deepest initial-rate discount. If your plan is 6–8 years, a 7/1 is the workhorse — the discount versus fixed is still meaningful and you have a year of buffer past the typical move horizon. A 10/1 makes sense when you expect to stay closer to a decade — the discount versus fixed is smaller but you get a full ten years of rate certainty. The wrong move is matching ARM type to a hold horizon you have not actually thought through.
What if rates drop instead of rise?
Then the ARM is even more advantageous — when the index falls, the new ARM rate (index + margin) drops too, capped only on the upside. In that scenario your ARM payment can actually decline at adjustment, which a fixed-rate loan cannot do without a refinance. The risk is asymmetric: ARMs benefit from falling rates and rising rates hurt them. The market consensus on rate direction is rarely a free lunch, though — pricing on ARMs already reflects market expectations.
Can I refinance an ARM into a fixed later?
Yes — refinancing is always available subject to qualification and closing costs. The standard playbook for ARM borrowers: use the initial-rate discount during the fixed period, then refi into a fixed-rate loan if rates have come down or stayed flat. The risk: if rates rise sharply BEFORE you refinance, you can be stuck either accepting the ARM adjustment or paying closing costs to refi into a higher-rate fixed. Run the numbers including a refi-cost-and-time scenario before you commit to the ARM strategy.
What's a rate cap?
ARMs come with three caps that limit how much the rate can change. The initial cap (often equal to the lifetime cap on first adjustment) caps the very first reset. The periodic cap (typically 2%) limits each subsequent annual adjustment. The lifetime cap (typically 5–6% above the initial rate) caps how high the rate can ever go. Caps are stated in your loan documents and are non-negotiable once you close. The simplified model in this calculator uses only the lifetime cap because it assumes a single adjustment scenario; the real ARM schedule with all three caps is more granular but also less useful for the high-level "ARM or fixed?" decision.
Are ARMs riskier?
They have a different risk profile. Fixed-rate loans concentrate risk at origination: you commit to a rate that may turn out to be higher than the market eventually offers. ARMs distribute risk across the rate-adjustment schedule: you get a lower starting payment in exchange for uncertainty about future payments. For a borrower who plans to be in the home longer than the initial fixed period AND has limited income flexibility to absorb a payment shock, fixed is the safer choice. For a borrower with a clear shorter horizon, strong income flexibility, and a refinance plan-B, ARMs are not categorically riskier — they are a different trade-off.

Picking between ARM and fixed? Let's quote both.

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