Ask how the venue serves cake
Some venues plate cake as the main dessert. Others cut smaller pieces after another course or place cake on a shared table for guests to take later.
Do not assume every venue uses the same slice size. Ask how cake is normally cut, plated and distributed before settling on the edible size.
Plan for the guests who will eat it
Use the full guest count when cake is the main dessert. When several other desserts are offered, the cake quantity may be reduced while still leaving enough for the people who want it.
Consider children, guests leaving early, late cake service and whether pieces will be boxed for family. These details can matter more than a generic servings chart.
Separate visual height from edible cake
A small cake can look lost in a ballroom, while a tall cake may overwhelm an intimate table. The stand, backdrop and flowers also affect how large the cake appears.
If more height is wanted than the guest count requires, discuss whether the design should use a stand, taller individual tiers or another display choice rather than simply ordering excess cake.
Give the venue a clear cutting instruction
The written order should state the expected serving basis. The venue should know which parts are edible, whether different tiers have different flavours and how any decorative pieces should be removed.
Send guest count, room type, serving style and other dessert plans together. That creates a more useful starting point than choosing tiers from appearance alone.