Smallest pillow takes 5c batter per cake (2.5 in each half) and serves 12 party - 18 wedding
Medium pillow takes 11c batter per cake (5.5 each half) and serves 24 party - 36 wedding
Large pillow takes 22c batter per cake (11 each half) and serves 50 party - 70 wedding
The Wilton info they provide is way off in both regards (except the servings for the smallest tier). I just don't get how they came up with those numbers?!
I hope that helps someone and prevents customers complaining there wasn't enough cake!