A nickel bag is a term used by drug dealers to reference 5 dollar worth of drugs. The term ‘nickel bag’ derive from the fact that a nickel is worth ‘5’ pennies. Nickel bags are mostly used for ‘Marijuanna’ sells. Other terms used for marijuana sizes are dime bag, dub sack, eight, quarter, and half among others.
That question can only be answered by the dealer, there is no standard amount weed for a nickel bag, it depends on the dealer and the weed’s quality, and thus it might differ from dealer to dealer.