CR for Characters with no Magic

[Toj]

I was wondering if anyone had a method or chart for CR modification when a character or NPC doesn't have gold and magical items for his level.

For instance, if you had a 15th level Orc, with only basic equipment, like a Sword, Shield, and Full plate. He doesn't have the gold and such that a PC would have, so how do you modifiy his CR to reflect that?

 

[Archer]

Without equipment an opponent is about half CR rounded up unless they have spells.

Spells can duplicate almost all magical equipment and since NPCs can use their entire allotment in one encounter they don't have much trouble using temporary means over permanent ones.