Ibonds vs pay down student loans


I have 10k in ibonds (x2 people) for 20k total
Issue date 4/1/2022

My student loan interest once I refinance will be around 4.7%
My treasury direct says I’m getting 6.48% return on my ibonds

Does it make sense to withdraw my ibonds and pay down my student loans? Seems like they are maturing better in the ibonds account. However, when you factor in federal tax, is it usually way less then what it sounds like (the full 6.48%)? Thanks!