I weigh 200# and I'm just over 6' tall and my top quilts are 40" wide.
I'm a gram weenie, so I think the average is wider.
Something to remember about quilt width. In a hammock, your bottom quilt wraps up around your sides partially, and the top quilt only needs to overlap that. However, if you use the quilt on the ground, it needs to be much wider because the ground doesn't come up and wrap around you like a hammock and bottom quilt.
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