Variable Rate Mortgage Calculation Adjustable Rate Mortgage Calculator – Payment Calculator – Adjustable Rate mortgage calculator adjustable rate mortgages (ARMs) offer a way for bargain-hungry borrowers to get the lowest mortgage rates and minimize their monthly payments. Unfortunately, they can also be unpredictable, because the rate you pay can change over time.What Is A 5 1 Arm Loan Mean Home Buying: What does "Conf ARM LIBOR 5/1 5-2-5" mean. – This means that the loan product is a 30 year term during which the first 5 years are at the fixed rate you’re being quoted. After those first five years (60 months) are up, the loan will convert to an adjustable rate mortgage (ARM) for the remaining 25 years.A 5/1 ARM is a type of hybrid mortgage where your interest is fixed for the first five years of the term and adjusts annually thereafter. With 5/1 ARMs, you have a low initial rate, but you risk your mortgage payments going up after year five.