I-bonds with a high fixed rate were available years ago. Those would be good to have now and in the future. Today's I-bonds have a very low fixed rate. If and when inflation goes back to normal you'll have a fairly low-yielding bond with a very small premium over inflation. Any guaranteed return over inflation is desirable, but I think you need to put some of your capital at risk to earn better returns if you want to fund a retirement. That means stock markets, other parts of the bond market, etc. I think for people who have not or don't want to put the time in to learn all this stuff, the best way to save for retirement is in a tax-advantanged account like an IRA, RothIRA, 401k, etc., using a retirement target-date index fund. Those funds take appropriate risk for your age and reduce risk as you get closer to retirement. Start there.