5/6, 7/6 and 10/6 identify the initial fixed years followed by six-month adjustment intervals. This model estimates the first reset and lifetime-cap stress payment, not a complete sequence of later six-month resets. Read the index, margin and periodic caps in the loan documents.
ARM Calculator
Understand the risks and rewards of an adjustable rate mortgage. See your initial payment, worst-case scenario, and fully indexed expected payment.
Loan & Initial Terms
Adjustment Rules (Caps & Index)
$3,648
Maximum Possible Payment
$2,690
Minimum Possible Payment
How Your Caps Work
Your ARM has a 2/2/5 cap structure. At your first adjustment in year 6, your rate cannot increase more than 2%. Each subsequent year, it cannot change by more than 2%. Over the life of the loan, your rate will never exceed 11.00%.
Adjustable-rate mortgage payment scenarios
Quick answer: An ARM begins with an initial rate for a fixed period, then adjusts using the loan index, margin and contractual caps. Model the first adjustment and a higher-rate case instead of relying only on the introductory payment.
Read the adjustment terms
Identify the initial period, index, margin, adjustment frequency, periodic cap and lifetime cap in the loan documents.
Stress-test payment shock
A higher rate applied to the remaining balance and term can materially increase the payment after the fixed period.
Compare the expected holding period
Selling or refinancing before adjustment is not guaranteed. Include transaction costs and the possibility that future rates are unfavorable.
Scenarios to calculate
- Compare a 5/6 ARM with a 30-year fixed mortgage.
- Model the first adjustment at the periodic cap.
- Model the lifetime-cap rate as a severe stress test.
Next: read the ARM risk and rate guide, compare a fixed-rate payment, model a possible refinance.
Fixed-Rate vs. Adjustable-Rate Mortgage (ARM)
When mortgage rates are high, Adjustable-Rate Mortgages (ARMs) surge in popularity because they offer a "teaser" rate that is significantly lower than a standard 30-year fixed loan. However, an ARM transfers the interest rate risk from the bank directly onto you.
How Does an ARM Work?
An ARM is typically formatted with two numbers, such as a 5/1 ARM or a 7/1 ARM.
- The First Number (5): This is the length of the introductory "fixed" period. For the first 5 years, your low interest rate is locked and guaranteed not to change.
- The Second Number (1): This indicates how often the rate can adjust after the initial period ends. A "1" means the rate will adjust once every year for the remaining 25 years of the loan. Some newer ARMs are structured as 5/6 (adjusting every 6 months).
Understanding the "Worst-Case Scenario" Caps
By law, lenders must protect borrowers from infinite rate hikes. They do this through three specific rate caps (e.g., 2/1/5 or 2/2/5).
- Initial Cap (e.g., 2%): The maximum amount the rate can increase on the very first adjustment (Month 61).
- Periodic Cap (e.g., 1%): The maximum amount the rate can increase on any subsequent yearly adjustment.
- Lifetime Cap (e.g., 5%): The absolute maximum your rate can ever increase above your initial teaser rate. If you start at 5%, your rate can never legally exceed 10%.
The Golden Rule of ARMs: Before signing an ARM, you must calculate the exact monthly payment if the rate hits its Lifetime Cap. If you cannot afford that "Worst-Case" payment, you should not take the loan. Our calculator perfectly simulates this worst-case scenario.
When is an ARM a Good Idea?
Despite the risks, an ARM can be a brilliant financial maneuver in specific situations:
- Short-Term Ownership: If you are absolutely certain you will sell the home or move within 5 to 7 years (e.g., military orders, a residency program). You get the ultra-low rate for the entire time you live there, and sell the house before the rate ever has a chance to adjust.
- Planned Refinance: You take the ARM to get the lowest payment today, with the aggressive plan to refinance into a 30-year fixed loan within the next few years when broader market rates drop. (Always remember: refinancing is never guaranteed if your credit drops or home values fall).
- Aggressive Paydown: You use the monthly cash flow savings generated by the low ARM rate to aggressively pay down the principal balance. By the time the rate adjusts upward, your loan balance is so small that the payment remains affordable.
Continue your financial research
Use these closely related USFinNexus guides and tools to plan your next step.
Illustrative comparison scenarios
| Term | Monthly P&I | Scheduled interest |
|---|---|---|
| 10 years | $3,406 | $108,773 |
| 15 years | $2,613 | $170,398 |
| 20 years | $2,237 | $236,813 |
| 25 years | $2,026 | $307,686 |
| 30 years | $1,896 | $382,633 |
Educational scenarios, not quotes, approvals, investment forecasts or tax advice. See methodology and limitations.