I am using geopandas to compute population per km2. However, I don't know if this transformation is using meters or kilometers.

gacs_df = gpd.GeoDataFrame(acs_df.merge(census_gdf2, on="geo_12", how="inner").drop_duplicates(subset='geo_12'), crs={'init': 'epsg:4326'})
gacs_df = gacs_df.to_crs({'init': 'epsg:3857'})
gacs_df["area"] = gacs_df['geometry'].area/ 10**6
gacs_df= gacs_df.to_crs({'init': 'epsg:32633'})
gacs_df["area"] = gacs_df['geometry'].area/ 10**6

I am replicating the code from Getting polygon areas using geopandas?. Thanks!!

  • 3
    Don't do any distance or area calculations in EPSG:3857, it is designed for web mapping (to fit most of the globe into 256x256 pixel tiles) and does not make any attempt to minimize distortion.
    – user2856
    May 22 '20 at 8:35

Both EPSG:3857 and EPSG:32633 have units in metres. If you divide the resulting area by 10^6 (=1,000,000), you get square kilometres (km²).

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