Heptagon Calculator

Your details

Pick whichever dimension you already know and enter its value below.
The length of one edge. All seven edges are equal in a regular heptagon.
cm
Area
363.3912cm²
Perimeter70cm
Side length (a)10cm
Apothem (inradius r)10.3826cm
Circumradius (R)11.5238cm
Short diagonal18.0194cm
Long diagonal22.4698cm
Interior angle128.5714
Exterior angle51.4286
Number of diagonals14

This regular heptagon has an area of 363.39 cm² and a perimeter of 70 cm.

  • Area scales with the square of the side: A ≈ 3.6339·a², so doubling the side quadruples the area.
  • Each interior angle is exactly 900°/7 ≈ 128.571°, and all seven sum to 900°. The exterior angle is 360°/7 ≈ 51.429°.
  • A heptagon has 14 diagonals: 7 short ones (18.02 cm) and 7 long ones (22.47 cm).
  • The circumscribed circle has radius 11.52 cm and passes through all seven vertices.

Next stepTo draw this heptagon with a compass, set the radius to 11.52 cm and step vertices around the circle at 51.429° intervals.

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