Adjustable Rate Mortgage Payment Calculator to Calculate ARM Payments and Interest

Adjustable Rate Mortgage Payment Calculator Sign

This free online calculator will calculate the fully amortizing ARM interest percentage adjustments along with the corresponding monthly payment changes.

Plus, the adjustable-rate mortgage payment calculator (also called a variable rate mortgage calculator) will also calculate the total interest charges you will end up paying on the ARM.

And finally, the calculator includes a feature that will allow you to view and print out a summary and loan amortization schedule.

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Adjustable Rate Mortgage Payment Calculator

Calculate an ARM payment amount along with the total interest charges and amortization schedule.

Special Instructions

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Selected Data Record:

A Data Record is a set of calculator entries that are stored in your web browser's Local Storage. If a Data Record is currently selected in the "Data" tab, this line will list the name you gave to that data record. If no data record is selected, or you have no entries stored for this calculator, the line will display "None".

DataData recordData recordSelected data record: None
ARM amount:ARM loan amount:Adjustable rate mortgage amount:Adjustable rate home mortgage amount:

Adjustable rate home mortgage amount:

Enter the dollar amount of the home loan (principal amount), but without the dollar sign and any commas.

Start rate:Starting rate:Starting annual interest rate:Starting annual interest rate:

Starting annual interest rate:

Enter the starting annual percentage rate (APR) of the home loan. Enter as a percentage without the percent sign (for 6%, enter 6).

# of years:Number of years:Loan term in years:Home loan term in number of years:

Loan term in number of years:

Select the term of the home loan in number of years.

Months before 1st rate adjust:# of months before 1st rate adjustment:# of months before 1st rate adjustment:Number of months before 1st rate adjustment:

Number of months before 1st rate adjustment:

Enter the number of months before the first rate adjustment will be made (usually 36, 60, 72, 84, 120, or 180).

Months between adjustments:# of months between adjustments:Number of months between adjustments:Number of months between adjustments:

Number of months between adjustments:

Enter the number of months between rate adjustments once the initial rate adjustment has been made (usually 12 months, but can be as many as 180 months).

Expected adj:Expected adjustment:Expected adjustment:Expected adjustment:

Expected adjustment:

Enter the percentage amount you expect the rate to increase or decrease by for each adjustment period. Enter a minus (-) sign before the percentage if you expect rates to fall during the course of the payoff. Enter as a percentage but without the percent sign (for .0025, which is 1/4 point, enter .25).

Rate cap:Interest rate cap:Interest rate cap:Interest rate cap:

Interest rate cap:

Enter the maximum allowable interest rate on the ARM. Once the maximum is reached, the Adjustable Rate Mortgage Payment Calculator will fix the rate for the remainder of the repayment term. Enter as a percentage without the percent sign (for 6%, enter 6).

Initial pmt:Initial payment:Initial monthly payment:Initial monthly principal and interest payment:

Initial monthly principal and interest payment:

Based on your entries, this how much your starting monthly house payment will be. This does not include property tax or insurance payments.

Total pmts:Total all pmts:Total of all monthly house payments:Total of all monthly house payments:

Total of all monthly house payments:

Based on your entries, this is the total of all of your monthly house payments (principal plus interest).

Interest cost:Interest cost:Interest cost:Interest cost:

Interest cost:

Based on your entries, this is how much interest you will pay between now and when you finish the home loan repayment.

Max payment:Maximum payment:Maximum monthly payment:Maximum monthly payment:

Maximum monthly payment:

Based on the entered rate cap, this is the maximum monthly payment for the ARM.

If you would like to save the current entries to the secure online database, tap or click on the Data tab, select "New Data Record", give the data record a name, then tap or click the Save button. To save changes to previously saved entries, simply tap the Save button. Please select and "Clear" any data records you no longer need.

Help and Tools


ARM definition, basics, types, and warnings.

Definition of Adjustable Rate Mortgage (ARM)

In case you're not familiar with the term, an adjustable rate mortgage (ARM), also referred to as a variable rate mortgage, refers to a type of mortgage (home loan) that has a fluctuating annual percentage rate (APR).

The amount and direction by which the ARM rate fluctuates are based on a variety of indices (US Treasury Bills, Cost of Funds Index, etc.), with the periodic adjustments occurring at preset intervals (usually once each year following the time the initial APR is guaranteed for).

Variable/Adjustable Rate Mortgage Basics

Since ARM loans shift the interest rate risk from the lender to the borrower, ARM loans typically offer lower interest rates than fixed APR loans. If interest rates rise, the ARM borrower loses money. If interest rates fall, the ARM borrower saves money.

The typical ARM loan has an initial APR that is guaranteed to remain constant for the first 1-15 years of the repayment period while stipulating a maximum APR adjustment that may occur each subsequent adjustment period (usually 12 months, but may be as many as 180 months). For example, an ARM loan may have an initial guaranteed APR of 6% for the first 36 months, after which it could increase by a maximum of .25% per year.

ARM loans usually come with a rate cap, which is the maximum APR that can be charged. So if an ARM loan has a rate cap of 10%, that will be most the lender can charge you during the repayment period. However, be aware that if you are being charged the maximum APR and the rate later falls to below the maximum, the lender will likely try to recover their losses by not lowering your APR (referred to as a carryover).

Of course, as the APR changes on an ARM loan, so do the size of the monthly house payments. As interest rates rise, the monthly payments rise, and visa versa. This can wreak major havoc on even the best of household budgets.

Types of Adjustable Rate Mortgages

Hybrid ARMS: Hybrid ARMs offer a mixture of fixed and adjustable-rate terms, and are usually listed as 3/1, 5/1, 5/5, 7/1, 10/1, or 15/15. The number appearing before the slash refers to the number of years the APR will be fixed, while the number after the slash refers to adjustment interval in years. Therefore the APR on a 5/1 ARM will be fixed for 5 years and may be adjusted once each year for the remainder of the repayment term. The adjustable-rate mortgage payment calculator on this page is based on a Hybrid ARM.

Interest-Only ARMS: Interest-only ARMs allow you to pay only the interest for a specified number of years -- usually for 3 to 10 years. This affords the borrower a low initial monthly payment, but at the expense of a much higher payment once the interest-only term has expired. Keep in mind that the longer the interest-only term, the higher will be the future principal plus interest payment.

Payment-Option ARMS: A payment-option ARM allows the borrower to choose among various payment options each month. In this type of an ARM, you may choose to make a principal interest payment (PI), or an interest-only payment, or a minimum payment. If you choose the latter option, be forewarned that it may lead to negative amortization, which means the minimum payment is less than the interest charged, which in turn will cause the principal (the amount you owe) to increase (balloon).

ARM Warnings

Be sure to be on the lookout for lenders offering teaser rates, or discounted rates. This is where ARM lenders offer an APR that is below the indexed APR just to get you to sign on the dotted line. Later, when the initial fixed term expires, you could experience a shocking payment increase that you may not be able to afford.

A second word of caution has to do with prepayments. Many ARM lenders assess stiff prepayment and conversion penalties if you make any attempt to shift the interest rate risk back on the lender. In other words, if you try to pay off the ARM early or if you try to convert the ARM to a fixed-rate mortgage, you may be assessed stiff prepayment penalties or conversion fees.

While it may be true that ARM borrowers have saved money historically, it's also important to realize the risk you are assuming before entering into an ARM. Lending institutions are much better equipped to assume the interest rate risk than you are. After all, they don't face the prospect of losing their job, and most of their risk is backed up with assets. You, on the other hand, could lose your job or end up upside down in your mortgage (your house is worth less than you owe), so please consider those possibilities before you enter into an adjustable-rate mortgage.

The Bottom Line

If you've spent any time in the financial calculators section of this website, you will know that I'm of the opinion that if you can't afford to pay cash for something, you can't afford it (as in, the opportunity costs of borrowing money can rob you of potential future wealth and happiness). Therefore, it doesn't matter if we're talking fixed, variable, interest-only, adjustable, or any other kind of "borrow from my future happiness to be happier today" type of mortgage, they are all just different ways of transferring your potential future wealth to the CEOs of lending institutions.

Adjust Calculator Width:

Move the slider to left and right to adjust the calculator width. Note that the Help and Tools panel will be hidden when the calculator is too wide to fit both on the screen. Moving the slider to the left will bring the instructions and tools panel back into view.

Also note that some calculators will reformat to accommodate the screen size as you make the calculator wider or narrower. If the calculator is narrow, columns of entry rows will be converted to a vertical entry form, whereas a wider calculator will display columns of entry rows, and the entry fields will be smaller in size ... since they will not need to be "thumb friendly".

Show/Hide Popup Keypads:

Select Show or Hide to show or hide the popup keypad icons located next to numeric entry fields. These are generally only needed for mobile devices that don't have decimal points in their numeric keypads. So if you are on a desktop, you may find the calculator to be more user-friendly and less cluttered without them.

Stick/Unstick Tools:

Select Stick or Unstick to stick or unstick the help and tools panel. Selecting "Stick" will keep the panel in view while scrolling the calculator vertically. If you find that annoying, select "Unstick" to keep the panel in a stationary position.

If the tools panel becomes "Unstuck" on its own, try clicking "Unstick" and then "Stick" to re-stick the panel.