What is the most common size for a baby or wedding shower two-tier cake. I was thinking 6 and 8 inches. But is 8 and 10 inches more common?

It depends on how many people you need to feed. I usually make a 10 inch and a 6 inch.

The size of the cake primarily depends on the number of servings that you will need. Sometimes people will go for a larger cake, even though a smaller one would have enough servings, because they like the look of the larger cake better.

There will be other desserts so it doesn't really matter how many servings. I will also make cupcakes. I'm just starting to use fondant and have spent many hours reading and watching tutorials on gum paste flowers. My how addictive! I've only made two 8-inch cakes and now want to do a two-tier.

If servings don't matter, then you may want to consider your design for the cake. Will you be putting lots of flowers on the tiers? You would then want to consider how much space you will need for these design elements.

Also, when it comes to two tier cakes I find it usually looks more complete if the tiers have four inches difference, rather than just two, but that is a preference thing.

When we make smaller two-tier cakes we try to do something like a 10-6 or 12-8 to leave more room for a design, an 8-6 or 10-8 would only leave 1 inch of workspace around the top tier.

Thanks so much for the information. I will go with a 6 and 10 inch. I thought there should be two inch difference but the 4 inches will be easier to work with. I'm so glad I asked!