Adjustable-Rate Mortgage Calculator
ARM Mortgage Calculator
Estimate payments on an adjustable-rate mortgage during the initial fixed period and after future rate adjustments. Model the ARM using index + margin, adjustment frequency, rate caps, and your own index scenario, then stress-test the potential payment if rates rise.
Last reviewed: September 1, 2026
Adjustable-Rate Mortgage Calculator
Model an ARM using index + margin, adjustment timing, caps, and a projected or stress-test rate path.
ARM Loan Details
Your ARM Results
Includes initial principal and interest plus entered property taxes, homeowners insurance, HOA fees, and estimated PMI when applicable.
Under the projected index path, you would pay about $128,175 in interest and an estimated $0 in PMI through year 7, with an estimated remaining balance of $287,040.
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Checking options does not change your calculator estimate. Loan availability, rates, and eligibility depend on lender and borrower qualifications.
| Month | Target Rate | Capped Rate | New P&I | Balance |
|---|---|---|---|---|
| 61 | 6.500% | 6.500% | $2,004 | $296,443 |
| 67 | 6.650% | 6.650% | $2,032 | $294,028 |
| 73 | 6.800% | 6.800% | $2,059 | $291,589 |
| 79 | 6.950% | 6.950% | $2,086 | $289,123 |
| 85 | 7.100% | 7.100% | $2,113 | $286,625 |
| 91 | 7.250% | 7.250% | $2,140 | $284,093 |
| 97 | 7.400% | 7.400% | $2,166 | $281,524 |
| 103 | 7.550% | 7.550% | $2,192 | $278,912 |
| 109 | 7.700% | 7.700% | $2,218 | $276,255 |
| 115 | 7.850% | 7.850% | $2,244 | $273,549 |
| 121 | 8.000% | 8.000% | $2,269 | $270,788 |
| 127 | 8.150% | 8.150% | $2,294 | $267,968 |
| 133 | 8.300% | 8.300% | $2,318 | $265,085 |
| 139 | 8.450% | 8.450% | $2,343 | $262,133 |
| 145 | 8.600% | 8.600% | $2,367 | $259,108 |
| 151 | 8.750% | 8.750% | $2,390 | $256,002 |
| 157 | 8.900% | 8.900% | $2,414 | $252,811 |
| 163 | 9.050% | 9.050% | $2,436 | $249,528 |
| 169 | 9.200% | 9.200% | $2,459 | $246,146 |
| 175 | 9.350% | 9.350% | $2,481 | $242,657 |
| 181 | 9.500% | 9.500% | $2,503 | $239,054 |
| 187 | 9.650% | 9.650% | $2,524 | $235,329 |
| 193 | 9.800% | 9.800% | $2,545 | $231,472 |
| 199 | 9.950% | 9.950% | $2,565 | $227,474 |
| 205 | 10.100% | 10.100% | $2,585 | $223,325 |
| 211 | 10.250% | 10.250% | $2,604 | $219,013 |
| 217 | 10.400% | 10.400% | $2,623 | $214,526 |
| 223 | 10.550% | 10.550% | $2,641 | $209,852 |
| 229 | 10.700% | 10.700% | $2,659 | $204,977 |
| 235 | 10.850% | 10.750% | $2,665 | $199,881 |
| 241 | 11.000% | 10.750% | $2,665 | $194,519 |
| 247 | 11.150% | 10.750% | $2,665 | $188,862 |
| 253 | 11.300% | 10.750% | $2,665 | $182,894 |
| 259 | 11.450% | 10.750% | $2,665 | $176,598 |
| 265 | 11.600% | 10.750% | $2,665 | $169,956 |
| 271 | 11.750% | 10.750% | $2,665 | $162,949 |
| 277 | 11.900% | 10.750% | $2,665 | $155,556 |
| 283 | 12.050% | 10.750% | $2,665 | $147,758 |
| 289 | 12.200% | 10.750% | $2,665 | $139,530 |
| 295 | 12.350% | 10.750% | $2,665 | $130,851 |
| 301 | 12.500% | 10.750% | $2,665 | $121,694 |
| 307 | 12.650% | 10.750% | $2,665 | $112,034 |
| 313 | 12.800% | 10.750% | $2,665 | $101,843 |
| 319 | 12.950% | 10.750% | $2,665 | $91,091 |
| 325 | 13.100% | 10.750% | $2,665 | $79,749 |
| 331 | 13.250% | 10.750% | $2,665 | $67,784 |
| 337 | 13.400% | 10.750% | $2,665 | $55,160 |
| 343 | 13.550% | 10.750% | $2,665 | $41,843 |
| 349 | 13.700% | 10.750% | $2,665 | $27,793 |
| 355 | 13.850% | 10.750% | $2,665 | $12,972 |
Important ARM Assumptions
This calculator models an ARM using the index, margin, rate changes, and caps you enter. It does not forecast SOFR or any other ARM index. Actual loan documents can include different adjustment dates, floors, rounding rules, margins, cap structures, and payment provisions. Use lender disclosures for the controlling terms of an actual mortgage.
Current ARM Rates
Compare ARM Mortgage Offers
The rate table is matched to the selected initial fixed period. Availability, pricing, and ARM structures vary by lender.
What is an ARM mortgage calculator?
An ARM mortgage calculator estimates how an adjustable-rate mortgage can behave over time. Unlike a fixed-rate mortgage, which uses one interest rate for the full loan term, an ARM typically has an initial fixed period followed by scheduled rate adjustments.
The calculator starts with your initial ARM rate and then models later resets using an index, lender margin, adjustment frequency, and rate caps. It recalculates the principal-and-interest payment when the modeled rate changes.
How ARM interest rates are calculated after the fixed period
Many adjustable-rate mortgages determine the new rate from a benchmark index plus a fixed lender margin. The resulting number is often called the fully indexed rate.
ARM rate target = index + margin
The target rate is still subject to the first-adjustment, periodic, and lifetime caps in the mortgage terms.
Understanding ARM types such as 5/6 and 7/6
ARM names generally describe the initial fixed period and how often the rate can adjust afterward. For example, a 5/6 ARM generally keeps the initial rate for five years and can then adjust every six months. A 7/1 ARM generally has a seven-year initial fixed period and annual adjustments after that.
3/1, 5/1, 7/1 and 10/1
The first number is the initial fixed period in years; /1 generally indicates annual adjustments afterward.
5/6, 7/6 and 10/6
The first number is the initial fixed period; /6 generally indicates adjustments every six months afterward.
ARM naming and adjustment conventions can differ, so verify the actual reset schedule in the lender's disclosures instead of relying on the product name alone.
What do ARM rate caps mean?
Rate caps are designed to limit how quickly and how far an ARM rate can change. The calculator separates the major cap types so you can match the structure in the mortgage offer you are evaluating.
First adjustment cap
Limits the rate change at the first reset after the introductory fixed period.
Periodic cap
Limits how much the rate can change at later scheduled adjustments.
Lifetime cap
Limits how far the rate can rise above the original ARM rate during the life of the loan.
Why the calculator uses an index scenario instead of predicting rates
Future ARM rates are unknown because the index used at future adjustment dates is unknown. Rather than pretending to forecast the index, this calculator asks you to enter the index at the first reset and an assumed change for later adjustments.
You can enter a positive number to model rising index values, zero for a flat path, or a negative number to test declining index values. The calculator then applies the entered caps to each modeled reset.
What is the ARM payment stress test?
The stress test intentionally assumes the ARM rises by the maximum permitted amount at each adjustment until the lifetime cap is reached. This produces a conservative payment path that can help you evaluate whether a potentially higher future payment would still fit your budget.
It is not a prediction of future mortgage rates. Actual ARM rates can rise, fall, or remain unchanged depending on the loan's index, margin, caps, floors, and market conditions.
When an adjustable-rate mortgage may be worth considering
An ARM may be worth comparing when the initial rate is meaningfully lower than available fixed-rate alternatives and you expect to sell, refinance, or otherwise pay off the mortgage before or not long after the first adjustment.
The lower introductory payment should not be considered in isolation. Review the adjustment rules and determine whether you could comfortably handle the modeled higher-payment scenarios if your plans change.
ARM calculator vs. ARM vs. fixed calculator
This page is designed to analyze the ARM itself: its initial payment, index + margin behavior, resets, caps, future payment scenarios, and amortization. If your main question is whether to choose an ARM or a fixed-rate mortgage, use the ARM vs. Fixed Mortgage Calculator, which compares both structures side by side.
Frequently asked questions
Can an ARM rate go down?
Potentially. If the underlying index declines, the fully indexed rate may be lower at a future reset. The actual result depends on the index, margin, caps, floors, and other loan terms.
What is the first adjusted ARM payment?
The calculator estimates it by applying index + margin at the first reset, limiting the rate change with the first-adjustment cap, and recalculating the payment using the remaining balance and remaining term.
What does a 2/1/5 ARM cap structure mean?
Cap notation varies, but it commonly refers to limits on the first adjustment, later periodic adjustments, and the maximum increase over the initial rate. Always verify the exact definitions in the mortgage documents.
Does an ARM payment change every month?
Usually not because of the interest rate. The ARM rate changes only at scheduled adjustment dates. Taxes, insurance, HOA dues, and mortgage insurance can change independently.
Is a 5/6 ARM the same as a 5/1 ARM?
No. Both generally have five-year initial fixed periods, but a 5/6 ARM may adjust every six months afterward while a 5/1 ARM generally adjusts annually.
Should I assume I can refinance before the ARM adjusts?
No. Refinancing depends on future rates, equity, credit, income, loan costs, and underwriting. Treat it as a possible future option rather than a guaranteed exit strategy.
Methodology and related ARM calculators
MortgagePaymentCalculator.io is published by Family Brands LLC. Calculator results are estimates for educational and planning purposes and are not mortgage offers, approvals, rate forecasts, or lender disclosures.