# What is the thickness of \hrulefill

This seems like a simple question ...

I know from this question that \hrule and presumably \hrulefill have a thickness of 0.4pt. I think \hrule is a primitive, so does that mean that you cannot change the thickness of \hrulefill?

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You can use \hrule height 4pt. See TeXbook chapter 21 page 221. –  Marco Daniel Aug 3 '12 at 16:13

The default height for \hrule is 0.4pt (not a parameter whose default value is 0.4pt) so you are correct that it may not be changed via setting a parameter. However \hrulefill is only a macro so you can change it if you wish.

It is defined by