If you are turning charms into hexagons, you do not have to precut your precuts. A square that is 1.5 inches bigger can make the hexie.
2.5 inch square makes a one inch hexie, fold fabric around 1" hexie paper, sew each corner, trim
3" square makes a 1.5" hexie - to make a 1.5" hexie start with a 3 " square
3.5" square makes a 2" hexie - 2 3.5
4 " square makes a 2.5" hexie - 2.5 4
5" square (charm) makes a 3.5 " hexie - 3.5 5
etc, etc