Menu

Mortgage ARM vs Fixed Rate Calculator

ARM Versus Fixed Rate Mortgage Calculator

Use this calculator to determine a fixed rate mortgage to a fully amortizing adjustable rate mortgage.

Please refer to the "Definitions" directly below the calculator area to help you understand each section of the calculator.

Mortgage ARM vs Fixed Calculator Definitions

  • Fixed Rate Mortgage
    • A Fixed Rate Mortgage has the same interest rate and monthly payment throughout the term of the mortgage.
  • Fully Amortizing ARM
    • This is the most common type of ARM, with a typical term of 30 years. During the initial period, the interest rate is fixed. After the initial period, the interest rate and monthly payment may adjust annually. Fully Amortizing ARMs have interest rate cap - there's a maximum amount the rate may change per adjustment, and a maximum amount the rate may change over the life of the loan. Below is a list of the most common types of Fully Amortizing ARMs.
  • Mortgage Amount
    • Expected balance for your mortgage.
  • Term in Years
    • The number of years over which you will repay this mortgage. The most common mortgage terms are 15 years and 30 years.
  • Expected Rate Change
    • The annual adjustment you expect in your ARM, after the initial period ends. The range for this calculator is minus 3% to plus 3%. Use a negative value if you believe interest rates will decrease, a positive value if you believe they will increase.
  • Interest Rate
    • Annual interest rate for each mortgage type. Typically an ARM will have a lower initial interest rate than a fixed rate mortgage.
  • Months the Rate is Fixed
    • This is the number of months the rate is fixed for an ARM. During this period the interest rate and the monthly payment will remain fixed. The rate will then adjust annually by the expected rate change.
  • Interest Rate Cap
    • This is the maximum interest rate for the life of this mortgage. The mortgage's interest rate will never exceed the interest rate cap.
  • Monthly Payment
    • Monthly principal and interest payment (PI) for the Fixed Rate Mortgage and the Fully Amortizing ARM.

Fully Amortizing ARM Table

Common Adjustable Rate Mortgages
ARM Type
 Months Fixed
10/1 ARM
 Fixed for 120 months, adjusts annually for the remaining term of the loan.
7/1 ARM
 Fixed for 84 months, adjusts annually for the remaining term of the loan.
5/1 ARM
 Fixed for 60 months, adjusts annually for the remaining term of the loan.
3/1 ARM
 Fixed for 36 months, adjusts annually for the remaining term of the loan.

Calculator Disclaimer

The Calculator Planning Tools are provided to you for illustrative purposes and are not guaranteed or intended to provide advice. The calculations you perform are based on the information you enter and should be used only as guidelines. The calculations do not represent terms or interest rates available from First Bank or whether you qualify for an account or loan. For more information please see our full Terms of Use or Contact Us if you have questions.