How many cups of frosting will it take to decorate 150 cupcakes?

It depends on how you are icing them, a 1M swirl will take more buttercream then the rose style, etc. But I usually count on it taking 4TBSP buttercream per standard size cupcake, 2TBSP for a mini cupcake. Multiply those numbers by how many cupcakes you are doing and you have the amount of buttercream you need.

I just bought the 1m tip and love the rose design it makes however i made one batch of frosting and it covered 24 cupcakes ive never measured how many cups one batch makes

thank you both!

Welcome happy baking