Vector -> Research tools -> Vector grid
Output grid as polygons
to create a 1000 by 1000 m grid from a shapefile. However, when I calculate the area of each grid cell via
attribute table -> field calculator -> Create a new field Output field name: area Output field type: Decimal number (real) Output field width: 15; Precision: 5
For the Expression to calculate the area I use:
When doing this, I get values which are bised by ca. 1% (too small): eg a grid cell area of 0.991639 km2 instead of 1.0 km2. The error seems to be bigger than just a rounding error and this adds up to a wrong total area of the shapefile.