What is the formula to find the volume of an octagon?

Answer 1

You don't find the "volume" of a flat figure. Perhaps you want its surface area.

The area for a regular octagon of side "a" is 2 (1 + root(2)) a2, where "root" is

the square root function. If it is not a regular octagon, I don't think there is a

simple formula to find the area - you'll have to split it up into simpler figures,

for example triangles.

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Answer #2:

Here is the formula, to which the first answer alluded in passing,

but which, for some reason, it did not explicitly present:

Volume of an Octagon = 0 .