Model builder - Calculate the centroid of a polygon

[MaryMulholland]

I would like to calculate the centroid (x and y co-ordinate) of a polygon using model builder - ArcGIS 10.1 Standard.  I don't have access to the tool Feature to Point as the standard licence doesn't allow this option and there doesn't seem to be a Calculate Geometry tool within model builder.  Can anyone help please!

[JustinMeyers]

you could use QGIS for free and not have the hassle with ARC. or you could right click on field and calculate geometry.