Determining Cake Servings

A question that I have received quite often is how to choose the right size cake for the amount of servings needed. So here you go. This serving guide is based on a
1.5"x 2" 3 layer cake:

Round
6" - 12 slices
8" - 20 servings
10" - 28 servings
12" - 40 servings
14" - 63 servings
16" - 77 servings
18" - 90 servings

Square
8" - 24 servings
10" - 30 servings
12" - 48 servings
14" - 63 servings
16" - 75 servings
18" - 100 servings

Rectangle
9"x13" - 30 servings
11"x15" - 60 servings
12"x18" - 72 servings