Key Takeaways A 0.5% drop in a 30-year fixed mortgage rate means homebuyers could afford roughly 5% more house without their monthly payment going up. Lower mortgage rates could bring more buyers into the housing market, driving up home prices in the process, one expert warned. However, instead of paying less per month, a lower mortgage rate could also allow you to afford a bigger house while keeping your monthly payment roughly the same. After a 20% down payment, with a 30-year fixed mortgage rate of 6.59%, you’d pay roughly $2,246 per month (excluding property taxes and fees). If the rate fell to 6.09%, you may be able to afford a $464,000 house while your monthly payment remained just above $2,200 a month.