I am using a cake mix for a 14, 12 and 10 inch cake. How do you know the quantity of cake batter to put in each cake pan?

Fill each pan with water about 2/3rds full then measure it.   This is how many cups of batter one needs for each size pan.   Measuring by the cupful is sooooo messy and inaccurate!  So here is a better way:...over the years I have found that a 14x2 round needs 2 cake mix batters; a 12x2 round uses 1 1/2 cake mix batters and a 10x2 round uses one mix.

These are things a 'professional' decorator needs to learn and quickly :)   Take each pan you ever use and figure out in advance how much batter it holds.  Use a permanant marker to write on the side or bottom of each pan so you remember :)

good advice, kakeladi

another way is to use this chart -- the wilton wedding cake data chart

then all you have to do is determine how many cups of batter your recipes make and write it down somewhere for reference and do a little math of course --

http://www.wilton.com/cms-wedding-cake-data.html

best to you

However..... since all the cake mixes got smaller around 2011, all bets are off depending on whether the baker "extends" or "supplements" the skimpy cake box mixes with other ingredients. 

I suggest you make ONE box mix recipe.  Measure the amount of batter.   THEN you'll know how much batter that single-box-recipe yields.  THEN you can use the wilton wedding cake data information above to figure out how many mixes you need for each pan.

Example:  I typically use doctored Duncan Hines mixes that are now 15.5 or 16.5 ounces each, then I add extra ingredients, and I end up with about 4-1/2 to 5 cups of batter -- per box. 

I use doctored mixes.  1 box mix doctored fills one 10" pan, 1 box mix doctored fills a three 6" pans and I have some left over.  I use this and a doctored box mix to fill three 8" pan.

To kakeladi ,

But what if the cake mix weight is only 425g (15oz)? Would it still be 1 cake mix for a 10-inch round pan?

The Betty Crocker SuperMoist products are all 517g (18.25oz). But I bought BC cake mix that is only 425g (15oz). What would be your suggestion? :)

sincerelyvanilla - Please read my earlier post.  Cake mixes in the USA were ALL 18.25 ounces for about 50 years.  Now they are NOT 18.25 ounces.  Recipes and measurements that were good for 50 years are different now.   People who have used "doctored box cake mixes" for 50 years have had to resort to all sorts of shenigans to get a similar result and yield per box mix.  Your best bet is to make the batter for your 425g (15oz) cake mix and measure it in a measuring cup.  You will then know exactly how many cups or portions of cups that mix makes.

Once you have that measurement, then you can follow the advice given above by kakeladi and fill your 10" pan 1/2 way or 3/4 full of water,  (as you would normally do for that recipe/box mix),  and then pour that water into a measuring cup and see how many cups of batter you will need for your 10" pan.

Then, you use the Wilton data and you will see that a 10" x 2" round pan generally requires 6 cups of batter for EACH 10" x 2" LAYER.  So, if you intend to make a four inch high tier with two 10x2 layers, you will need a total of 12 cups of batter.

Sorry folks for the delay in replaying.  I moved and do not have internet connection for awhile - I use a public computer at the library:(

Regarding the smaller size of the cake mixes here in the US......If you read my replies on the thread I posted for the
WASC cake you will see that even though the size of the mixes are a bit smaller now I still get the amounts of batter I mentioned in my above reply on this thread.........

I cannot emphize enough how messy and INaccurate measuring cake batter by the cupfull is and should be advoided at all costs.  As Apti said in her reply just above, Yes, do it ONE! time while making your own chart.....but be sure, Sure SURE you scrape out ALL the batter each time you fill that cup. 

Learning how much batter each recipe yields (whether box mix or scratch) and what pan(s) it fits in is a real sign of a '-pro' decorator:)   I have found that many of the cupfull amounts given on the Wilton chart are not accurate enough.  Yes, one could use it as a guide to start with, but you still need to Make your own chart!  Then you will be sure you get enough batter in each pan.  When I had my bakeries if I had to measure each cupfull of batter each time I wanted to bake I'd still be measuring today! :(  

one could pour the batter into a large measuring cup -- I have an eight cup glass Pyrex one that is perfect for this little chore -- once you measure the yield of your recipe write it down and then you have it forever --

I didn't know about the "pour water into pan, then into measuring cup to see how much batter needed for a specific pan"  trick when I made my first 3D Skull cakes.  Oh....no..... I did it the hard way......

I poured red velvet batter into the skull pan cavities, then poured it back out into measuring cups, then poured the red velvet batter back into the skull pan cavities. 

My kitchen looked like a mass murder had taken place.    Thick, bleeding, red velvet batter everywhere.......

YIKES apti!   The water idea works w/o the mess :)