Cake Portion Guide: What Size Of Cake Should You Make?
Serving Guide — CAKEify
Cake Servings Guide – Iced Jems
Wedding Cake Serving Guide - HEB
Cake Servings Chart - Sweet Celebrations, LLC. Colorado Custom Cakes & Confections. (Attention: This website is Currently Inactive, Owner is Away)
The Royal Bakery - These are the serving guides I use for 1" x 2" x 4" (or 5") tall slices. I created these myself. Square cakes are easy to work out -