How do I adjust a recipe that makes 2 8" layers down to 2 6" layers...or up to 12" layers for that matter??? I don't want to waste ingredients or make layers too thin....HELP!!! Thanks!!

Are you baking from scratch or mixes?
For two 6" round layers, fill each pan 2/3rds fill; use the rest for cupcakes OR make a 3rd layer to fz until you need another.
For a 12" round uses the batter from 1 1/2 mixes. My *original* WASC recipe is perfect for the 12"er
Knowing how much batter each pan holds is the key to answering your ?. Fill each pan 2/3rds full w/water and measure it. That's how much batter you need.
For mixes here's a breakdown so you don't have to measure (I've done it for you over the years hehe
two 8" rounds or one 8" sq OR 8x12 sheet OR one 10" round OR most any Wilton shaped pan OR three 6" rounds -each use the batter from one cake mix.
Batter from 1 1/2 mixes OR one recipe of the *original* WASC recipe fills:
one 12" round; OR one 10" sq; OR one 9x12 sheet OR three 8" rounds
Batter from 2 cakes mixes fills:
one 12" sq; OR one 14" round OR combinations of 12" along w/one 8" round; etc. OR one 12x16 sheet.
All the above pans are 2" deep.

Cake pans the same depth, based on an 2x 8" round pan recipe

1. scale down to 2x 6" round - multiply each ingredient by 0.60

2. scale up to 2x 12" round - multiply each ingredient by 2.25

Hi,
Can anyone help me.
I have a lovely 8inch round vanilla cake recipy but need to scale it up to a 10inch square! I have no idea about figures and am struggling.

Thanks in advance from an amature looking to get better cake maker,
Claire xx

The most reliable way is to know all of your pan measurements in cubic inches and how many cubic inches of finished cake your recipe will make. Then you can scale it up or down directly. PM me with your email address and I will send you the chart I made.