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ARM vs. Fixed-Rate Mortgage Calculator

Compare an adjustable-rate mortgage to a fixed-rate mortgage across three scenarios: rates stay flat, rise gradually, or hit the lifetime cap. See the real payment risk.

ARM vs. Fixed Comparison

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Init. cap / Yearly cap
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Max above initial rate, ever
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Margin added to index
Fixed Monthly Payment
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per month
ARM Starting Payment
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ARM Worst-Case Max Payment
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Highest monthly payment
Worst-Case Jump vs Start
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Increase from initial ARM payment
Fixed Total Interest
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ARM โ€” Rates Flat
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Index stays flat
ARM โ€” Rates Rise
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+0.5% per year
ARM โ€” Worst Case
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Rates hit lifetime cap

ARM payment scenarios assume index rates stay flat, rise 0.5%/yr, or immediately hit the lifetime cap. Actual rates depend on market conditions. This is not a quote.

โš–๏ธ ARM vs. Fixed: Which Is Better?

Choosing between a fixed-rate mortgage and an adjustable-rate mortgage (ARM) is a balance between guaranteed stability and potential savings. A fixed-rate mortgage locks in your interest rate for the life of the loan, while an ARM offers a lower introductory rate that adjusts after a set period.

๐Ÿ—๏ธ Understanding ARM Structures

The most common ARM is the 5/1 or 7/1. The first number represents the fixed-rate years, and the second represents how often the rate adjusts thereafter. Caps like 2/2/5 protect you by limiting how much your rate can jump at once and over the lifetime of the loan.

๐Ÿ’ก When an ARM Makes Sense

An ARM is often a strategic choice if you plan to sell or refinance within 5-7 years, or if you expect your income to increase significantly before the first adjustment period. The initial monthly savings can be substantial compared to a standard 30-year fixed rate.

โš ๏ธ The Primary Risk
If you are unable to sell or refinance before the adjustment period, your monthly payment could increase by $500 or more depending on market conditions. Always ensure you have a "plan B" for your mortgage.

SOFR (Secured Overnight Financing Rate) is the benchmark interest rate used by lenders to determine your ARM's adjustment. Your rate is calculated as SOFR + Lender Margin. Because SOFR is tied to broader economic conditions, your rate will fluctuate based on the Federal Reserve's monetary policy.

Today's Avg Rates

30-Year Fixed6.85%
15-Year Fixed6.11%
5/1 ARM6.44%
Source: Freddie Mac PMMS ยท Updated Weekly