Square
area:
length times width (L x W)

Cubic
area: length
times width times height (L x W x H)

Circumference
of
a
circle: diameter times pi (

d*pi),
where
pi = 3.14

Area
of
a
circle:
radius (1/2 the diameter) squared, times pi (3.14)

* When calculating for a round structure, remember
that your earthbag
walls are going to be about a foot in
thickness. Consequently, a
structure with a 15 ft outer diameter will have about
a

13 ft
inner
diameter, give or take for the thickness of your
plaster both inside
& outside.

Length
of
arc
of circle: diameter
times pi times angle of sector, divided by

360.

Example: Your structure is round & you're trying
to figure out your
door.

If your proposed door is 3 ft wide and your structure
is 10 feet in
diameter,

then 3 * 360 = 1080 /3.14 = 343.9 / 10 = 34 degrees.

You can reverse this: if diameter is 10 feet & you
know the angle
of your sector is 30
degrees,
then pi * 10 * 30
= 942. Divide this by 360 and you have 2.6 feet (the
length of your
arc - or, more practically, the width of your dome's
door or window).