I know it's been a while since this was asked, but I had this very same question this evening and I found this post while searching for the answer. I just finished testing this for myself and, in my very small sample of 4 ounces of peanuts, the net weight with shells was 116 grams and without the shells, it was 82 grams. This means the actual peanuts are about 70% of the total weight. Be aware, that I gave no mind to peanut skins as I assumed they would be negligible since my accuracy level was a full gram.

it is the shelled peanut which is 3/4 of the unshelled peanut

Thanks

Thank you for this reply.

I couldn't do the weighting....

Only thing to consider in your results is whether the peanuts were raw or roasted.

The results you've got means that the price of the peanuts itself (without the shell) is 41% more  (1.41x) then the price of the whole peanut.

This can then be compared to the price of 100% pure peanut butter.

The downside of peanut butter is that one can't tell if moulded (and hence toxic) peanuts were used as ingredients...