Because trifolds and z-folds are both folded in thirds, they have the same area for content sections. With a trifold/z-fold on 8.5' x 11', each section or fold would be approximately 8.5' x 3.67'. With a bifold at that same size, each section or fold would be approximately 8.5' x 5.5'. Each section of a trifold/z-fold on 11' x 17' paper would be 11' x 5.67'. Each section of a bifold on 11' x 17' would be 11' x 8.5'.