A mortgage in which the monthly principal and interest payments remain constant throughout the life of the loan.This type of Mortgage is called Fixed Rate Mortgage(FRM). If the fixed rate mortgage is calculated for 30 years, it is called as 30 year fixed mortgage rates(FRM). If it is for 20 years, it is called as 20 year fixed mortgage rate(FRM) and if it is for 10 years, it is called as 10 year fixed mortgage rate(FRM) calculation. Free simple/fixed rate mortgage(FRM) loan calculator online. Find the monthly mortgage payments for different home loans.