The measure of each exterior angle of a regular octagon is ______.

We know that the measure of each exterior angle of a regular polygon is $\frac{{360}^o}{\mathrm{n}}.$

Where ‘n’ is the number of sides of the polygon.

We also know that an octagon has 8 sides, i.e. n = 8.

So, the measure of each exterior angle of the regular octagon $=\frac{{360}^o}{8}={45}^o$