*sighs*

A dime is not a measure of mass, it is simply the amount of weed a dealer is willing to sell you for $10.

Usually that is less than a gram.

Likewise a dub or 20 sack is just 20$ worth of bud, however much that might be.

PS. A dime bag is almost always a rip off. Save your lunch money for 1/8th at least =P