I want to calculate the area of counties (1st admin level) in Kenya in ArcGIS. What is the right projection for that? I know I should use an equal area projection, but when I use them (I tried six different) it varies heavily to the county areas given in wikipedia. I could also use UTM37, but by definition it's not an equal area projection.

  • Did you always get the same answer regardless of which equal-area projection you used? If not, then something erroneous is happening and you will need to tell us more about how you are computing those areas. If so, then everything is working fine and you should challenge the Wikipedia figures.
    – whuber
    Commented Nov 28, 2015 at 21:04
  • No, the values varied. But I am wondering why they are all different to the "official" area data. Commented Nov 28, 2015 at 21:14
  • Since they varied, there must be some aspect of your calculation that is incorrect. That would explain the discrepancies with Wikipedia, too.
    – whuber
    Commented Nov 28, 2015 at 21:26
  • These are my number for Kenya (admin_0 level): UTM37: 586416 Albers Equal Area:585983 Lambert Equal Area:509155 Eckert2,4,6: 589920 Wikipedia: 581309 Commented Nov 28, 2015 at 21:54
  • 2
    If you are using the same spherical datum for different equal-area projections, then any differences among your results will arise only from floating-point imprecision (and should be extremely small).
    – whuber
    Commented Nov 30, 2015 at 15:10