ARM vs Fixed Mortgage Calculator
ARM vs fixed mortgage calculator. Compare 5/1, 7/1, 10/1 ARMs to a 30-year fixed across hold periods. Total cost, breakeven, payment-shock + worst-case rate analysis.
ARM vs Fixed Mortgage Calculator
Side-by-side comparison
| Metric | Fixed | ARM |
|---|---|---|
| Monthly P&I (initial) | — | — |
| Monthly P&I (after reset) | (same) | — |
| Total payments over hold | — | — |
| Total interest over hold | — | — |
| Remaining balance at hold end | — | — |
How to use the ARM vs fixed calculator
Enter loan amount + total term + your hold
Loan amount: principal at origination. Total term: usually 30 years for both ARM and fixed. Hold period: how long you plan to keep the loan before selling or refinancing. ARM math is dominated by this. If you'll sell BEFORE the ARM resets, ARM strictly wins.
Enter the fixed rate
Current 30-year fixed rate quote from your lender. As of mid-2026, prime borrowers see 6.5-7.5% for conventional 30-yr fixed.
Enter ARM initial rate + fixed period
ARM teaser rate is typically 0.5-1.0% LOWER than fixed. 5/1, 7/1, 10/1 ARMs: fixed for 5, 7, or 10 years, then resets annually. 7/1 is most common. Enter the initial rate and the fixed-period length.
Enter your expected reset rate
This is the speculative part. Conservative: assume rates rise to current fixed-rate level or 1-2% higher. Pessimistic: assume rate-cap (typically +5% above teaser). Realistic: somewhere in between. The reset rate is YOUR forecast — the calculator doesn't predict it.
Read the verdict
Three outcomes: (1) STRONG ARM — you'll sell/refinance before reset. ARM almost certainly wins. (2) ARM still wins — savings during initial period exceed the higher payments after reset. (3) Fixed wins — reset rate is high enough that ARM costs more overall. Run multiple scenarios with different reset rates to stress-test.
ARM vs fixed — the rate bet most homeowners get wrong
Adjustable-rate mortgages (ARMs) offer a lower initial interest rate than fixed-rate mortgages for a defined period (typically 5, 7, or 10 years), then reset annually based on a reference index (SOFR since 2023, LIBOR before) plus a margin. The deal: pay a lower rate now in exchange for taking interest-rate risk later. ARMs got a bad reputation during the 2008 housing crisis, but the post-2014 ARM market has stricter qualification standards, lifetime rate caps, and clearer disclosure. For the right borrower with the right hold horizon, an ARM can save tens of thousands of dollars. For the wrong borrower, it\'s a recipe for payment shock and financial distress.
The math
If your initial ARM rate is 6.5% vs 30-year fixed at 7.25%, you save ~0.75% annually during the initial fixed period. On a $400K loan, that\'s ~$200/month, $2,400/year, $16,800 over 7 years (a 7/1 ARM). If you sell or refinance BEFORE year 7, those savings are locked in — ARM strictly wins. If you hold longer, the math depends on what happens at reset. The 7/1 ARM typically has caps: 2/2/5 means rate can rise max 2% at first reset, max 2% per year after, max 5% total over loan life. So a 6.5% start has a hard ceiling of 11.5%, no matter what. Most ARMs reset to "index + margin" — SOFR + 2.75% margin would mean ~7.75% at typical SOFR rates.
ARM economics are dominated by ONE question: will you sell or refinance before reset? Answer "yes" with high confidence → ARM almost always wins. Answer "uncertain" → reset risk usually kills the ARM math.
When ARMs make sense
Three classic ARM-friendly scenarios. (1) Short-term ownership: corporate relocators, military families with PCS orders, careers requiring frequent moves, "starter home" buyers planning to upgrade in 3-5 years. (2) Career-trajectory income growth: residents/fellows expecting partner-level salary jumps, founders with funded startups, high-bracket professionals with expected income doubling. The ARM\'s reset becomes affordable with future income. (3) Falling-rate environments: when rates are at cyclical highs and likely to fall, a 7/1 ARM lets you ride the curve down before locking in a refinance. The 2022-2023 rate-spike + 2024-2026 stabilisation rewarded many ARM-takers.
ASEAN context
ASEAN markets dominantly use variable-rate or short-fixed-period mortgages. Singapore: floating-rate (SORA-pegged) and fixed-for-3-or-5-years are common. Pure 30-year fixed is rare and expensive. Malaysia: BR-pegged variable rates dominate. Indonesia, Thailand, Vietnam: variable rates linked to local benchmarks. The ARM-vs-fixed comparison framework still applies, but the comparison is "short-fixed-period vs longer-fixed-period" rather than US-style ARM vs 30-year fixed.
10 Things to Know About ARM vs Fixed
ARM = Adjustable-Rate Mortgage. Lower initial rate, resets annually after fixed period.
5/1, 7/1, 10/1: initial fixed period 5, 7, or 10 years; then resets annually. 7/1 most common.
ARMs typically 0.5-1.0% lower than 30-yr fixed during initial period. Discount narrows in flat-yield-curve environments.
Caps: typically 2/2/5 — max 2% first reset, max 2% per year after, max 5% lifetime above initial.
ARM reset = index + margin. Index: SOFR (since 2023, replaced LIBOR). Margin: 2-3% typical.
US median home tenure ~7 years — many borrowers sell before ARM resets. ARM math wins in those cases.
Post-2014 ARMs require "ability to pay" qualification at fully-indexed rate, not teaser. Reduces payment-shock risk.
Pre-2008 ARMs: option-ARMs, neg-am, 2/28 hybrids exposed homeowners to crushing payment shock. Banned or rare today.
ARMs are not for first-time buyers with thin emergency reserves. Reset payment shock can destabilise household finances.
Best ARM candidates: known short hold periods, growing-income trajectories, falling-rate cycles.
Frequently asked questions
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First number: years of initial fixed rate. Second number: how often the rate adjusts after the initial period. 5/1: fixed for 5 years, then adjusts every year. 7/1: fixed for 7 years, then annual adjustments. 10/1: fixed for 10 years, annual after. There are also 5/6 ARMs (adjusts every 6 months) — rarer. The longer the initial fixed period, the smaller the rate discount vs 30-yr fixed.
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Limits on how much the rate can rise. Standard caps: 2/2/5 means (1) first reset can\'t raise rate more than 2%, (2) subsequent annual resets can\'t raise more than 2%, (3) lifetime maximum is 5% above the initial rate. A 6.5% ARM has hard ceiling of 11.5% no matter what. The caps were added post-2008 to prevent the kind of payment-shock disasters that wrecked subprime borrowers. Pre-crisis ARMs had no meaningful caps; today\'s ARMs are much safer.
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Post-2023: SOFR (Secured Overnight Financing Rate) dominates. 1-year Treasury is also common for ARMs. 11th District Cost of Funds Index (COFI) for some California ARMs. LIBOR: phased out in 2023 — if you have an older LIBOR-indexed ARM, it transitioned to SOFR. Your loan documents specify the exact index. The reset rate = index value at reset date + your loan\'s margin (set at origination, typically 2-3%).
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Yes, anytime. Most ARM-takers plan to do exactly this if rates fall favourably. The play: take the lower ARM teaser rate, then refinance to fixed when rates drop or before the ARM resets. Risks: (a) rates DON\'T drop, leaving you stuck at the ARM reset, (b) credit quality deteriorates (job loss, divorce, medical event), making refi qualification harder, (c) home value drops, pushing LTV above refi thresholds. Always have a fallback plan if refinance isn\'t possible at the moment you need it.
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Yield curve. When short-term rates are much lower than long-term rates (normal/steep yield curve), ARMs (priced off short-term) are MUCH cheaper than fixed (priced off long-term Treasury). 2022-2023 saw an inverted yield curve where ARMs were barely cheaper than fixed — making ARMs less attractive. Mid-2026 yield curve is normalising; expect ARM discounts to widen back to 0.5-1.0% range. Yield curve dynamics are the macro environment you\'re betting on with an ARM.
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No — you set it. The calculator doesn\'t predict future rates. It runs the math given YOUR assumed reset rate. Run multiple scenarios: conservative (rates stay flat → reset ~= current fixed), pessimistic (rates rise 2%+ → reset hits cap), realistic (rates drift up modestly). The answer changes with each assumption. ARMs are inherently a rate-environment bet.
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Interest-only ARMs let you pay only interest (no principal) during an initial period — typically 5-10 years. Lower payments but you build NO equity. After the I/O period ends, payments jump dramatically as you must amortize the remaining balance over the remaining term. These were major contributors to the 2008 crisis. Today they\'re rare and restricted to high-credit borrowers with substantial reserves. Avoid for primary residences unless you have a very specific cash-flow reason and a clear payoff plan.
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Excellent timing. If rates seem likely to fall meaningfully: (a) take the ARM at the lower initial rate, (b) refinance to a lower fixed when rates drop. Worst case if rates DON\'T fall: you ride out the initial period (5-10 years), then face the reset. Even then, the savings during the initial period are often enough to make the ARM net-positive. The 2010-2020 zero-rate environment was the ARM golden age — many ARM-takers refinanced repeatedly down to sub-3% fixed loans.
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No. Loan, rates, hold, reset assumption — every input stays in your browser. The ARM-vs-fixed comparison runs entirely client-side. Open DevTools → Network when you click Compare and you\'ll see zero outbound requests.
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CFPB Consumer Handbook on Adjustable-Rate Mortgages — required disclosure, accessible at consumerfinance.gov. HUD Handbook 4000.1 for FHA ARM rules. Federal Reserve ARM Booklet for plain-English consumer guide. Lender Loan Estimates are required to clearly show initial rate, fully-indexed rate, caps, and reset schedule.
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