The average interest rate on a 30-year fixed mortgage is 6.86%, compared to 6.91% a week ago.The average rate on a 15-year fixed mortgage is 5.97%, down 0.00 percentage point from the previous week.Homeowners should compare their existing mortgage rate with current market rates to determine if refinancing is worth the cost.Factors such as the economy, benchmark interest rates, and borrower-specific factors can affect mortgage rates.