I have to make 40 cupcakes for this coming Sunday-and I really want to make sure I have enough frosting made AHEAD of time, but I'm really not sure how much to make. I don't want to be making/coloring frosting at the last minute, and I'd rather not have 3 containers full when I'm done! (Although if I had to choose, I'll take option B ).

They're your standard size CC- not jumbo or mini - and I'm going to just do a swirl-type thingy because they'll all be topped with gum pate plumerias or hibiscus.
And the biggest dilemma- I'm going to make 6 different colors, and not the same number of cupcakes per color either...like I said I'd prefer to make TOO much, rather than not enough....but I'd appreciate any sort of guideline I can get. Thanks!!

What type of buttercream do you use - how much does each batch make?

Whenever I have piped a swirl of icing on cupcakes, I found that it took way more icing than I anticipated. Of course, the amount of icing you need will depend on the tip you use and how big the swirl is. Sorry I can't give you a more specific answer.

If you have leftover icing, it can be frozen for later use.

A batch of BC that uses 2 lbs of powdered sugar should be enough for 40 cupcakes. (Your swirl doesn't need to be tall, since you're topping with a flower, right?) But when you divide into lots of colors somehow you always need extra. What are your proportions? I'd probably do two batches (2 lbs PS each), use the first for whatever color or colors you need the most of, and the second batch divided into smaller portions for the colors you need less of.

I have found that a standard swirl takes about 1/3 cup of bc per cc.

Hi Everyone! Thank you all for the advice, I'm sorry I didn't get a chance to respond sooner ...Soooo I made two double batches of BC icing, and did a couple of "tests" with the extra cupcakes I made. I found that 1/3 Cup was enough for me to frost 2 cupcakes, and still have some left over (with the right amount of frosting I wanted on each CC). So I figured out how many CC I would need for each color, which ended up being: 10 Lime Green, 8 Turquoise, 6 Orange, 6 Pink, 6 Yellow, and 4 purple-and just went from there. I divided it up into smaller containers and made all the colors the night before. I ended up running out of icing on my last color (which was orange) but luckily I had a can of Wilton icing in the pantry so I was in luck! I couldn't believe that when all was said and done, I had made enough frosting for all 40 cupcakes. I wasn't scrambling at the last minute, down the wire sweatin' bullets, trying to turn white icing into the perfect shade of lime green or neon pink to finish them all! Yay!!