Fixing a home loan is a 50-50 bet, researcher Canstar has found.Canstar looked at data going back 21 years to see how homebuyers fared if they chose a three-year fixed rate over a standard variable rate loan.It found there were 126 months when it would have been financially rewarding to fix and 128 months would it would have been better to choose a variable rate loan.The analysis was based the average rates of the Big Four banks over the 21 years, assuming that loans were interest only.The best time to opt for a three-year fixed rate was in November 2011; a borrower with a A$300,000 loan would have saved $15,071 over three years by fixing.The worst time to fix was in March 1995, when a borrower with a $300,000 loan would have paid an extra $22,476 over three years by fixing.