I'm struggling to figure out what size tiers for a wedding cake to serve around 180 people with a combination of round and square tiers.  They would like either 3 or 4 tiers and will serve the top tier.

 This is what I use. I got it on CC. Don't remember who posted it

6" round x 7" square x 12" round x 14" square = 190

6" round x 8" square x 12" round x 14" square = 198

Thanks ladies!