Is there a chart you follow or use as a bench mark to determine how much BC you need to frost a say 8 inch double layer cake?

I usually make the BC icing that has 2lbs of sugar...and thats never enough...and I end up making 3 batches.

How much BC do you make at a time? Do you just double/triple the recipe. I use Indydebi's BC recipe.
And how should I estimate I would need for my cakes?

if you check out the wilton website, they have a guide as to how many cups of bc you need for each size of cake.
you can just multiply or divide the recipe, its easy to do.
xx

I use Sharon Zambito's BC Recipe. l prefer it over any I've tried as I too was tired of running out. It using 5lbs of PS with 5 Cups of High Ratio Shortening. It fills a 5 QT Kitchenaid to the very top. Comes out smooth as silk everytime. I LOVE IT!

Wilton does have a chart, but it is only a guideline. Not knowing just how much you ice your cake with, makes it hard to offer an exact number. Some apply icing thinner or thicker than others.