The surface area of a hexagonal prism can be calculated using the formula 3*(2+30.5)*a2, where a is the length of one of the sides of one of the hexagon bases. Note that this formula only applies for regular hexagonal prisms, where the sides on the hexagon bases are the same length.
If the hexagon bases are irregular on a hexagonal prism, there is no standard formula for surface area. In order to calculate the surface area, the surface area of each individual surface must be calculated and added together. The area of rectangle sides can be calculated by multiplying length by width. An irregular polygon must be divided into smaller polygons in order to calculate its area.