A hexagonal prism always has 18 edges. There are six edges around the top and bottom hexagon faces, equaling 12 edges, and another six where the faces are connected on the sides, for a total of 18 edges.
A hexagonal prism is the basic three-dimensional representation of a hexagon, which is a two-dimensional polygon with six sides. The prism consists of two hexagons that are parallel to each other, which may or may not be the same size. They are connected with straight lines from a vertex on one hexagon to a vertex on the other. The connecting lines form quadrilaterals on the sides, either squares or rectangles. In total, a hexagonal prism has eight faces, with six quadrilateral faces and two hexagon faces. Additionally, a hexagonal prism also has 12 vertices, six located at each vertex of each hexagon face.
A prism can be regular or irregular, depending on the shape of the two-base polygons. In the case of a hexagonal prism, it is only a regular hexagonal prism if the two hexagons are the exact same, and each hexagon is comprised of six equal sides. Any shape where the two-base polygons consist of varying side lengths is an irregular shape.