Regular heptagon is shown below:

Let the side of heptagon be 'l'. Then area 'S' of heptagon of side length 'l' is given by;

S = (7 /4) l

^{2}cot (π / 7),

Hence S ≈ 3.634 l

^{2},

Interior angle and exterior angles of heptagon are 128.571° and 51.43° respectively. The number of diagonals and Triangles in a heptagon are 14 and 5 respectively. Number of triangles are composed by lining the diagonals from a given vertex. Addition of interior angles in a heptagon is equals to 900°. Diagonals are calculated as 7. (7 - 3) / 2 = 14.

Addition of interior angles can be calculated as (7 − 2) · 180° = 900°.

Central angle of heptagon will be derived by dividing 360° (or 2π radians) with 7 and hence 360° / 7 = 51.43°.

Perimeter of a heptagon is P = 7.1.

Area of a heptagon can also be calculated by (Perimeter + Apothem) / 2.

If we calculate the parallel sides in a heptagon, there will be utmost 3 pairs for a convex heptagon. Otherwise it depends on type of heptagon.