Hello fellow bakers! I noticed that I'm really struggling with trying to figure out how much batter and frosting to use for cakes. Does anybody have a good chart or reference you would like to share?

I did a 1/4 sheet cake this weekend and ran out of buttercream about half way through. It was heavily decorated with rosettes. 

A rule of thumb is to expect to use 1 recipe of icing (using 2# of sugar) for each box of mix or recipe used.  As far as how much batter per pan you are going to have to work that out.   I  remember these:  most Wilton shaped pans, one 10" round; one 8" sq and one 8x11 (1/4 sheet) pan used one cake mix.  12" round, 10" sq use 1 & 1/2 recipes of mix; 14" round and 12" sq and 12x16 rectangle (1/2 sheet) uses two mixes.   

take each pan you have, fill it 2/3rds full of water, then empty it into a measuring cup to see how many cups of batter that pans needs.   Mark you pan on the side or bottom w/a permanent marker so you remember.