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).