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A pyramidal frustum is a frustum made by chopping the top off a pyramid. It is a special case of a prismatoid.
For a right regular pyramidal frustum, let 
be the slant height, 
the height, 
the bottom base perimeter,
the top base perimeter,
the bottom area,
and 
the top area. Then the surface
area (of the sides) and volume of a pyramidal frustum
are given by
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(1)
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(2)
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The geometric centroid of a right pyramidal frustum occurs at a height
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(3)
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above the bottom base (Harris and Stocker 1998).
The bases of a right regular 
-gonal frustum are regular polygons
of side lengths 
and 
with circumradii
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(4)
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where 
is the side length, so the horizontal separation between corresponding vertices
on top and bottom is
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(5)
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and the edge length is
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(6)
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(7)
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The slant height of a lateral face is
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(8)
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The triangular (
)
and square (
)
right regular pyramidal frustums therefore have side surface
areas
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(9)
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(10)
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The area of a regular 
-gon is
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(11)
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so the volumes of these frustums are
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(12)
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(13)
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