User blog comment:RemosPendragon/Imperial Worlds/@comment-1536954-20140603044121

Aestimare isn't detailed rather extensively, but effectivly it is how important a world is to the imperium.

This is what I found on the web by a guy quoting a White Dwarf article:

Noting that all of these work on a scale of 1-1000, with 1 being the best and 1000 being the worst. I think the scale slides evenly through the letters as well, so a B1 grade world is worth only a little less than an A 1000.

A class planets are vital worlds, essential to the imperium to keep that area/sub-sector etc. They cannot be lost unless something forces them to become useless/destroyed (Warp Storm, Chaos Cult, etc) Examples: Cadia, Terra, Macragge?

B class are hive worlds, forge worlds, or worlds of significant military or strategic importance, but not absolutely vital to the continuation of the imperium. Examples could include Necromunda, Hydraphur, Gryphonne IV, Stygies IV

C class worlds that should be held, but are allowed to fall if defending them would endanger B or A Class worlds. Example: Khai-Zann, Taros?

D class tactical or sparsely populated worlds (Including Agri worlds) - I&#39;d say this one is right on the money, except that agri-worlds would be influenced by the system they are in. They would be far more valuable in a Hive world system than a mining system for example.

E class research or outpost world (including mining operations) - I'd say this is perfect, I might also include Penal colonies in this group, as no one really cares if a few convicts die.

F class non populated world - I might add alien occupied/alien majority here, as its of no value to the imperium, but is still worth a look for colonization efforts.

G class dead world (exterminatus) - I'd say the 1-1000 range here indicates how devastating the Exterminatus was/if the planet has regenerated any biomass etc.