To use the
Soil and Bark Volume Calculator, simply enter the width, length, and thickness of your
area to be covered, click on whether you are measuring the thickness in feet or inches, then click on the Calculate button. The calculator will estimate the number of cubic yards of
soil or bark that will be required. 
Odd Shaped Area?
You could revert to your high school geometry, or you can try this:
1 Make a rough drawing of your area
2 Divide that area into sections. Choose a dividing line that will
create something close to a rectangle. Close is good enough.
3 Use the calculator above to determine the cubic yards
required for each section, and then just add them together.
Example 1:

This gives you at least a rough estimate of how
much you need to order, without resorting to higher
math.
Just enter the dimensions into the calculator above.
You should be fairly close. The excess from one area should
offset the deficit in another. 

Example 2:
When you get the results on section 3, cut them in
half. That should give you a fairly accurate result,
when you add up the calculator results for section 1, section
2, and half of section 3. 

