Regular Nonagon (9 sides) — free printable diagram

How many sides does a nonagon have?

A nonagon is a nine-sided shape — a polygon with 9 sides and 9 corners. A regular nonagon has 9 equal sides and 9 equal angles of 140°.

Sides

9

Vertices (corners)

9

Interior angles add up to

1,260°

Each interior angle (regular)

140°

Each exterior angle (regular)

40°

Diagonals

27

Lines of symmetry (regular)

9

Also called

nine-sided figure, nine-sided polygon

• The interior angles of any nonagon add up to (9 − 2) × 180° = 1,260°.
• A regular nonagon has every angle the same, so each one measures 1,260° ÷ 9 = 140°.
• A nonagon has 27 diagonals — 9 × (9 − 3) ÷ 2.