Hi all! I am doing a wedding cake for 150 people and I'm not sure what tier sizes I should do. This is the biggest cake I've done, so I want to be sure it looks good. We're doing square tiers and will be offsetting them. What would you do? Thanks!

I'd do a 14" square x 9" square x 6" square for 156 servings...
if they want to keep a 1st anniversary tier, add a 4" square to it for 164 servings.

If you'd like to figure out additional combinations for off-set stacking, here are the right angle measurements to see what size is required for it to fit:

4" 5.66
5" 7.07
6" 8.49
7" 9.9
8" 11.31
9" 12.73
10" 14.14
11" 15.56
12" 16.97
13" 18.38
14" 19.8
15" 21.21
16" 22.63
17" 24.04
18" 25.46

There are cake servings charts on the Wilton website and also a good one at Earlenescakes.com The number of servings from a given cake depends upon the size of the slice you plan to serve. Wilton has two serving sizes, a small one for wedding cakes (i.e. there will be lots of other food and all you want is a small piece of cake) and another for party sized servings. Earlene's uses a more generous serving. Use google to find them but both are worth looking at and bookmarking for future use.
Of course you can always estimate servings from the size of the serving you plan to use, and with square cakes it is even easier than with round. For example if you have an 8" square tier, each side is 8" long. If you want your servings to be 2" x 2" (on top, we're ignoring the height of the cake), you can draw your cake, and draw lines for cutting slices every 2 inches. You'll see that you can fit 16 2" squares on an 8" square cake.

Industry standard servings are 8 cubic inches:
http://www.wilton.com/cakes/making-cakes/baking-wedding-cake-2-inch-pans.cfm

(1x2x4 or 2x2x2).

Check out this link.. so awesomely helpful.. this is my 'go to guide' when organise all of my quotes.. with the exception of novelty sculpted cakes. HTH

http://shinymetalobjects.net/cake/calculator/cakulator.cgi?group_round=11&.defaults=Reset&option=3&option=Select+Cakulator&servingSize=Continue&serving_width=1&serving_length=2&serving_height=4&.cgifields=group_sheet&.cgifields=group_square&.cgifields=group_round

THanks everyone! This is very helpful! I'm always afraid to choose layers that are too close in size and having it look bad. I'll definitely use this info!