HOUSTON – Over the last year, millions of Americans have refinanced their homes to save money by taking advantage of low interest rates. 2020 interest rates vs. 2021 interest ratesIn November and December of 2020, you could get a 30-year mortgage for 2.5% interest. To get a general idea of how much you can save, you can use NerdWallet’s mortgage refinance calculator. If we knew we would be in our hypothetical home at least 4 years, Smith says refinancing it would be worth it. She said if interest rates have dropped at least 1% since the first refi, it might make sense.