Regular Dodecagon (12 sides) — free printable diagram

How many sides does a dodecagon have?

A dodecagon is a twelve-sided shape — a polygon with 12 sides and 12 corners. A regular dodecagon has 12 equal sides and 12 equal angles of 150°.

Sides

12

Vertices (corners)

12

Interior angles add up to

1,800°

Each interior angle (regular)

150°

Each exterior angle (regular)

30°

Diagonals

54

Lines of symmetry (regular)

12

Also called

twelve-sided figure, twelve-sided polygon

• The interior angles of any dodecagon add up to (12 − 2) × 180° = 1,800°.
• A regular dodecagon has every angle the same, so each one measures 1,800° ÷ 12 = 150°.
• A dodecagon has 54 diagonals — 12 × (12 − 3) ÷ 2.