Well I have FINALLY begun my first wedding cake - all are baked with the exception of the largest 16".

QUESTION: How much frosting in Cups do I need to crumb coat and cover the following:

16" round x 3 H
12" round by 3
2- 9" rounds x 3
8" round x 3
6" round x 3
2-5" rounds x 3

I'll be getting that ready tomorrow. Thanks so much for your help!

Not knowing if your 3" tall layers are single layer without filling, or how many times they may be torted to include BC filling, I'd guestimate you'll need between 27-33 lbs. of buttercream if you're also using it for decorating. HTH.