What is the interior and exterior angle of a regular octagon?

To work this out, all the external angles of any shape add up to 360°, so all we need to do to work the external angle out is divide 360° by the number of sides giving us a sum of 360 divided by 8 sides = 45°; so now we have the exterior angle we can easily find the internal angle, we do this by subtracting the external angle which in the case of an octagon is 45° from 180° thus giving us 135°, of course this is only going to work on a regular shape with equal sides as an irregular shape is going to have different angles but will still total 360°.

The interior angle of a regular octagon is 135° and the external 45°.

By tash2010