Joined: May. 99
Welcome to Diana's Desserts Discussion Forum.
When you need to know how much batter a particular size cake pan (in this case, a bundt pan) will hold, fill the pan up to the inside rim with water using a liquid measuring cup. This will give you the exact amount of liquid that the pan will hold, although you wouldn't fill it with that much batter or the cake would overflow while baking.
You should only fill a bundt pan half way full with batter because when you're baking with bundt pans, the cake tends to dome so you don't want to overfill the pan.
Most store-bought cake mixes make 4 to 5 1/2 cups of batter so if you want to use a 10-inch (or 10-cup) bundt pan instead of your 12-cup capacity bundt pan, there should be no problem, but remember to measure the pan first with water. For instance, if your new 10 cup (or 10-inch) pan holds 10 cups of water, then it will easily hold (for baking purposes) as much as 5 to 6 or so cups of batter.
Hope this information helps you out.