Hi I would like to simply calculate areas of a area-shape file in square meters or in acres (ha).
I didn't find that functionality in the vector tools.
Could anyone here help me with that?
Use the field calculator (Layer>Open attribute table>Field Calculator/Ctrl+I or right click shapefile>Open attribute table>Field Calculator/Ctrl+I). There is an operator "area" that will calculate the area of each row in the table. All units will be calculated in the units of the projection, so you probably want to project it to a projection that uses feet or metres before doing that, rather than lat/lon.
This can also be done with Vector|Geometry Tools|Add/export geometry columns, which creates a new shapefile with area and perimeter (or length) columns added.
Edit: (using the tool above, you can also unselect "save as new shape-file" in V1.8, the shapefile is now only updated!)
Using the field calculator is probably a better idea, though, as it doesn't require the creation of a new shapefile.
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