Calculating a Mesh Area

This post focuses on using the 3D Printing Addon to calculate the surface area of a mesh.  This can translate into useful information, as in the case when designing a backyard, and you want to determine the surface area of a patch of grass that is not nicely geometric.

First enable the 3D Printing Toolbox Addon.

Next select your mesh, (or the parts that you want to calculate), and in the toolbar (T) select the 3D Printing tab, and press Area and this should produce a calculation for you in the box at the bottom.  Note that the area value is in Blender Units.  So if you are working in Blender Units, then you are set and no further work is needed.

However, if you are working in feet (like me) for example, you'll need to do a conversion.  You need to determine the ratio between Blender Units and feet in your scene.  To do so, you can switch between the Blender Units (None) and Feet (Imperial) in the World panel

 and compare the values of the standard cube length.

After gaining this ratio, you can use simple scale arithmetic to determine the area of your mesh in any type of units you are working in.  Note that this addon can also be used to calculate Volume as well.