You’d need to get an average rate under 6.07% over the following 4 years for the 1-year rate to be worth it.
So ask yourself – “once my first year is up, could I get an average interest rate of less than 6.07% (on average) for the next 4 years?
If you think the answer is ‘yes’, go for the 1-year.
If you think the answer is 'no', take the 5-year.
The purpose isn’t to guess the interest rate precisely right. It’s about giving you a frame of reference so you decide which rate to choose.
You can download the spreadsheet I showed above here.
So, what interest rate should I go with?
Generally, if people think interest rates will go up, they fix for longer.
If people think rates will head down, they fix for shorter.
Sure, the 5-year rate is cheaper today. But in 3 years, you might kick yourself.
Just like many of us are kicking ourselves for taking the cheaper 1-year rate in 2021.
We saved a bit of money in the 1st year. But we are paying for it now.
Remember, the goal isn’t to get the lowest rate today. It’s to get the lowest average over 5 years.
A higher rate today might save you money in the long run.