Geographic Information Systems Stack Exchange is a question and answer site for cartographers, geographers and GIS professionals. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Possible Duplicate:
Calculate area between contour lines on a DEM with Qgis 1.8.0-Lisboa

Based on a DEM of a whole country I have reclassified altitudinal bands with steps of 100 metres (100-200, 200-300...). Then I polygonized the bands in order to get shapefiles and summarized them with the tool „Singleparts to Multiparts“

Now I have one entry in the attribute table for each altitudinal band.

I would like to calculate the area of each band but no matter what I write or select at the field calculator settings, the result is alwasy the same (Even if I change the CRS). And when I save it (finishing the edit mode) the number turns to 0. What am I doing wrong?

I am using qgis 1.8.0.

share|improve this question

marked as duplicate by whuber Jan 3 '13 at 18:00

This question was marked as an exact duplicate of an existing question.

What value returns typing $area in the raster calculator ? – Curlew Jan 3 '13 at 17:52
For the new field / column being calculated, what type is it? Integer, Double Precision, String? – Willy Jan 3 '13 at 23:27
The value in the attribut table is integer. The area I would like to calculate in real. I always get numbers like 0.0484618034274718 no matter if I change the CRS for the project or the layer. I dont know what type this is cause I always get the same and cannot compare anything. – Sebastian Jan 4 '13 at 9:23

In the function list on the left hand side of the field calculator, click the plus sign on the Geometry function. In the expanded list of geometry functions, select $area.

share|improve this answer

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