Financing tools
Fixed vs. Adjustable Rate
An ARM's lower initial payment is real. So is the payment after it adjusts. See both, using your own assumption for what the rate might be later — not a forecast this tool makes for you.
Direct answer: a fixed rate never changes. An ARM starts lower, then adjusts to an index plus a margin after its initial period — nobody can tell you today what that rate will be. Enter your own assumption to see the payment impact, and compare total interest and remaining balance over your expected holding period.
Loan basics
Fixed-rate scenario
Adjustable-rate (ARM) scenario
Payment comparison
| Scenario | Payment | When |
|---|---|---|
| Fixed | $2,661 | Every month, entire term |
| ARM — initial | $2,398 | First 5 years |
| ARM — after adjustment | $2,873 | Remaining term, at your assumed rate |
At adjustment, the payment shifts by $475 higher — recast on the remaining balance and remaining term at your assumed rate, the way a real ARM adjustment works.
At your 10-year horizon
- $262,595
- Fixed — total interest paid
- $259,722
- ARM — total interest paid
- $343,250
- Fixed — remaining balance
- $343,460
- ARM — remaining balance
Know your own timeline
The right answer depends on how long you expect to hold the loan.
An ARM makes the most sense when you have a realistic reason to believe you won’t hold the loan past the fixed period — a planned move, a refinance target, or a short-term hold. If you can’t say why you’d leave before it adjusts, that’s worth weighing carefully.
Methodology
How this comparison works.
- Fixed payment uses the standard amortization formula at one rate for the full term.
- ARM initial payment uses the initial rate for the full term, the standard way ARM initial payments are calculated.
- ARM payment after adjustment is recast on the loan’s remaining balance and remaining term at your assumed post-adjustment rate — the way a real ARM adjustment actually works, not a fresh full-term calculation.
This tool models exactly one adjustment. Real ARMs can adjust repeatedly (commonly annually after the initial period) — one adjustment keeps the comparison usable while still showing the real mechanism and the real risk.
The assumed post-adjustment rate is entirely a number you choose. It is not a prediction, forecast, or current rate — try several values to see how sensitive the comparison is.
Worked example (hypothetical)
A $400,000 loan, 30-year term: a 7% fixed rate produces a payment of roughly $2,661. A 5-year ARM starting at 6% produces an initial payment of roughly $2,398. Assuming the rate adjusts to 8% after year 5, the payment recasts on the remaining balance to roughly $2,873 — a jump of about $475 a month. Over a 10-year horizon, total interest paid is close between the two (roughly $262,595 fixed versus $259,722 ARM in this example) — the ARM’s lower early payments partly offset its higher later payments, though the comparison is entirely dependent on the assumed post-adjustment rate.
Downside cases
- If rates are meaningfully higher at adjustment than assumed here, the real payment shock could be larger than this comparison shows.
- An ARM held past its initial period without refinancing carries real payment uncertainty — worth planning for the higher end of what you consider plausible, not just the most optimistic case.
National considerations
ARM adjustment mechanics (index, margin, caps) are set by the specific loan program and change over time with market conditions.
Utah considerations
ARM availability and initial-rate discounts vary by lender and loan program available in Utah.
Author: Todd McClean, Realtor® | Real Estate Investment Strategist, Mountainland Realty, Inc.. Reviewed July 19, 2026. This tool provides general real estate information and is not legal, tax, accounting, lending, securities, commodities, or financial-planning advice.
Next step
Weighing a fixed rate against an ARM?
A strategy review can help think through how long you’re likely to hold the loan.