AI'm going to be making around 250 cupcakes how do i figure out how much icing i will need?

I work with weights, not volumes. So I know that a regular cupcake swirl on one of my cupcakes weighs around 2oz. So I multiply that by 250 to get the total amount of frosting needed. I guess if you use cups... maybe you know that say 2 cups of icing is enough for 10 cupcakes (I have no idea!!)...so multiply 2 cups by 25 to get enough for your 250 total cupcakes.
 

I use grams when weighing my icing, and my swirls are roughly 33-35 grams, so 35 grams being 1.234 ounces, and my recipe makes 6 lbs 6 oz , so 102  ounces dived by 1.234 = 82.6 swirls per batch. 250 divided by 82.6 = 3.02 batches of icing, so I will try to make sure I make them closer to 34 grams to make sure I have enough for all 250, and don't have to make another batch for those last 2 cupcakes!