Many drawing pencils come with a grade that determines their hardness and darkness. For example, H determines how hard a pencil is, while B tells you how black the actual graphite is. H pencils are more dense but contain less graphite, so they’ll leave lighter lines. B pencils, however, are much softer and contain more graphite, which means they’ll produce darker marks on paper.
Both pencils also have a secondary number classification that ranges from 2 through 8, with the higher numbers being softer and darker for B and lighter and harder for H. The lower numbers are more moderate in their respective letter characteristics.