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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?

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Follow up question: I have a layer in State Plane NAD83. When I use these commands it creates the area in feet. What if I want acres or square miles? Thanks – C_K Apr 17 at 23:26
Hum...this is not an answer. Maybe you can add a commentary bellow the question. – Andre Silva Apr 18 at 0:43

2 Answers

up vote 13 down vote accepted

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.

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up vote 3 down vote

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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protected by underdark♦ May 6 at 12:48

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