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Loan comparisons · ARM or fixed

ARM vs Fixed Calculator for Lender Websites: Show the Whole Term, Not Just the Teaser

This tool runs an ARM and a fixed-rate loan over the same amount and term. It shows the ARM's initial and adjusted payments, the fixed payment, each loan's total cost and which is cheaper over the life of the loan. It helps a loan officer tell whether a borrower is chasing a low start or planning around a short stay.

The ARM question is really a "how long will you keep this loan?" question; this calculator gets the borrower asking it.

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Start free on Originator What the numbers tell you about the borrower
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This is the calculator your visitors use. Enter numbers to see it work.

Loan Comparisons

What is the borrower trying to figure out with an ARM vs fixed comparison?

Whether the cheaper starting payment is worth the uncertainty. They have seen an ARM quote below the fixed rate and want to know what happens after year five or seven.

Take an illustrative $400,000, 30-year loan: fixed at 6.5% is about $2,528 a month, while a 5/1 ARM starting at 5.75% is about $2,334, saving roughly $194 a month for five years. If the rate then resets to 7.5% and stays there, the payment climbs to about $2,742 and the ARM ends up costing around $52,000 more in total. That reversal is what keeps borrowers up at night, and what makes them ask for help.

How should a loan officer use an ARM vs fixed calculator with prospects?

Use it to have the time-horizon conversation early. Embed it on your ARM or loan-options page and send it to buyers who mention a job relocation, a starter home or a planned refinance.

The lead shows you the fixed rate, the ARM start rate, the fixed period, the adjusted rate the borrower assumed and the resulting totals. The adjusted rate is the tell: a borrower who typed a reset barely above the start rate has not priced in risk, while one who entered a rate at or near the cap is stress-testing responsibly.

A good first call covers three points:

  • How long they expect to keep the home or the loan, compared with the fixed period they entered.
  • What the actual caps and margin are on the ARM you would offer, using the rate caps definition to explain them.
  • Whether they would still qualify comfortably at the adjusted payment, not just the start payment.

For borrowers also weighing an interest-only structure, the three-way ARM comparison is the natural next step.

What arrives in your CRM

What the numbers tell you about the borrower

  • ARM Adjusted Rate (%)Reveals the borrower's risk assumption. A reset rate close to the start rate suggests optimism you should gently correct; a rate near the lifetime cap means they are already planning for the worst case.
  • ARM Fixed Period (years)Compare it with their stated plans. If they entered 7 years and mention moving in four, the ARM may fit; if they plan to stay twenty years, the fixed loan deserves a serious look.
  • Lower Lifetime CostShows which option won under their assumptions. Borrowers who submit even when the fixed loan won are often looking for reassurance rather than a lower start, and appreciate a clear explanation.
  • ARM Adjusted PaymentThe payment you should qualify them against mentally. If it would strain their budget, discuss reserves and a fixed alternative before the borrower commits emotionally to the lower start.

A first message that uses their numbers

What is a compliant first message to an ARM vs fixed lead?

Hi {first name}, thanks for comparing the ARM and fixed options on our site. Whether an ARM makes sense mostly comes down to how long you expect to keep the loan and how a higher payment after the fixed period would fit your budget. I can walk you through the actual adjustment caps on current ARM programs whenever suits you.

When discussing ARMs, describe the index, margin and caps accurately and avoid implying the borrower can refinance before the reset, since future rates and approval are not assured.

Where this calculator earns its place

  1. 01

    Loan programs or ARM explainer page

    Visitors reading about ARMs want to test the numbers immediately.

  2. 02

    Relocation and short-stay buyer campaigns

    Borrowers who expect to move within the fixed period are the strongest ARM candidates and benefit most from the comparison.

  3. 03

    Rate-quote follow-up when both options were priced

    Lets the borrower model different reset scenarios on their own before your next call.

Limits worth knowing

  • The calculator holds the adjusted rate constant for the rest of the term; real ARMs can adjust again each period within caps, up or down.
  • Lifetime totals assume the borrower keeps the loan to maturity, which overstates the relevance of late-term costs for anyone who sells or refinances.
  • Payments are principal and interest only, so qualifying should use the full housing payment.

Calculator disclaimer: Estimates only. The ARM total assumes the adjusted rate holds for the rest of the term; real ARM rates move with market indexes within the loan's caps. Confirm terms with your lender.

Definitions in the calculator

Adjustable-rate mortgage (ARM)
A mortgage whose rate is fixed for an initial period and then resets at set intervals, based on a market index plus a margin, within rate caps. A 5/1 ARM is fixed for five years and then adjusts once a year. This calculator compares one ARM scenario against a fixed-rate loan of the same amount and term.
Fixed-rate mortgage
A mortgage whose interest rate and principal-and-interest payment stay the same for the whole term. It usually starts at a higher rate than an ARM’s initial rate, in exchange for certainty. Its total cost in this calculator is known in advance, while the ARM’s depends on the rate you assume.
Total cost
The sum of all principal and interest payments over the full term. The ARM total here combines payments at the initial rate with payments at the adjusted rate for the remaining years. The difference between the two totals is the lifetime savings or extra cost of choosing the ARM.
Initial rate
The introductory interest rate during the ARM’s fixed period, often lower than a comparable fixed-rate loan. The gap between it and the fixed rate is what the ARM saves during the fixed period. Whether that saving survives depends on how high the rate goes after the reset.
Fixed period
The number of years the initial rate is locked before the first adjustment, such as 5 on a 5/1 ARM or 7 on a 7/1. If you expect to sell or refinance before it ends, the ARM’s later rate may never apply, which is why this period weighs heavily in the comparison.
Adjusted rate
The estimated rate after the fixed period ends. In practice it equals the index value at reset plus the margin, limited by the caps, and it can change again at each later adjustment. This calculator holds your estimate for the rest of the term, so testing a few values shows how sensitive the result is.
Rate caps
Limits on how much an ARM rate can change: at the first adjustment, at each later adjustment, and over the life of the loan. They are set in the loan documents and vary by lender and product. Entering the highest rate the caps allow gives a worst-case view of the ARM in this comparison.
Loan term
The length of time scheduled to repay the loan in full. A longer term lowers each payment but keeps the balance outstanding longer, so total interest rises. The same term is applied to both loans here, and the ARM’s term includes its fixed period.

Terms on this page

Pairs well with

ARM Calculator

Let borrowers see the reset payment on their own screen before you ever have to explain it.

FAQ · 8 questions

Questions about this calculator

How does the calculator work out the ARM's adjusted payment?

It amortizes the loan at the initial rate for the fixed period, then re-amortizes the remaining balance over the remaining years at the adjusted rate you entered. On $400,000 over 30 years, five years at 5.75% leaves a balance near $371,000; spread over 25 years at 7.5%, that becomes a payment of about $2,742. The adjusted rate is then held for the rest of the term.

Why can an ARM cost more overall even though it starts lower?

Because the early savings are small relative to the extra interest charged after a higher reset. In the example, the ARM saves about $194 a month for 60 months, roughly $11,600, but pays a higher rate on a large balance for 25 years. The total gap depends heavily on the adjusted rate you assume, so try several.

What adjusted rate should I enter?

Try at least two: a moderate case and a worst case built from the loan's caps. Because this tool holds one rate for the rest of the term, the harshest test is the start rate plus the lifetime cap, the ceiling later adjustments can climb to. If the ARM still looks acceptable at the worst case, the risk is easier to live with. Your loan officer can tell you the actual index, margin and caps for a specific program.

Does the comparison account for selling or refinancing before the reset?

Not directly; it assumes both loans run the full term. If you expect to sell or refinance within the fixed period, focus on the monthly savings during those years and treat the lifetime totals as a downside scenario. Keep in mind a refinance depends on future rates and qualifying, neither of which can be known today.

Are borrowers who use an ARM calculator good leads for a loan officer?

They tend to be informed and specific. Someone comparing ARMs usually already has quotes or is weighing a particular purchase timeline, which makes the first conversation substantive. The risk is a borrower anchored on a teaser payment, so the value you add is a frank discussion of caps and reset scenarios. Ask early how long they expect to keep the home; the answer usually decides whether the ARM discussion is worth continuing.

Can I set up a separate follow-up sequence for ARM leads?

Yes. On plans with webhooks you can give this calculator its own webhook URL and send its leads to a HighLevel, Zapier or Make workflow built for ARM conversations, while other calculators feed your general pipeline. The payload includes the fixed period and adjusted rate as fields, so the sequence can reference the borrower's own scenario.

Should I show ARM vs fixed to first-time buyers?

You can, but frame it carefully. First-time buyers often have thinner reserves, so a payment increase after the fixed period hits harder. Many LOs place this calculator on a loan-options page rather than in a first-time buyer funnel and discuss it once the borrower raises ARMs. The decision always rests on the borrower's plans and budget, not on a page placement.

Does PrequalFunnel quote ARM rates or margins?

No. The calculator uses whatever rates the borrower enters and produces an estimate. It does not price loans, pull credit or issue a pre-approval. Actual ARM terms, including the index, margin and caps, come from you and the lender, with the disclosures your program requires. Think of the calculator as the borrower's sketch pad: it organizes their assumptions so your first call can replace them with real program terms.

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