Take the 2-minute tour ×
Geographic Information Systems Stack Exchange is a question and answer site for cartographers, geographers and GIS professionals. It's 100% free, no registration required.

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?

share|improve this question
    
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 '13 at 23:26
    
The two answers provided work but they are a bit slow to implement especially when one is trying to determine the area of many polygon vector files. Is there not a plug-in or some other way to get the area of a polygon simply by right clicking the polygon? The answers provided end up with a new field attribute (i.e. area) but the value doesn't update if the polygon is changed. So, in many cases there is no need to have the area displayed in a separate field attribute. If the area could just be shown as a number in a small chart, on the bottom of the page, etc it would be sufficient. So, is the –  David Aug 16 '13 at 23:06

2 Answers 2

up vote 25 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.

share|improve this answer

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.

share|improve this answer
1  
I'm not able to select the Field Calculator button so thank you –  boulder_ruby Jan 22 at 15:34
    
To use the Field Calculator, I believe you have to hit edit (the pencil) first. After that it should light up. Confusing! –  jocull yesterday

protected by underdark May 6 '13 at 12:48

Thank you for your interest in this question. Because it has attracted low-quality answers, posting an answer now requires 10 reputation on this site.

Would you like to answer one of these unanswered questions instead?

Not the answer you're looking for? Browse other questions tagged or ask your own question.