What size butter sticks are you using? mine are 1/2 cup size sticks.

In the US, I believe the conventional packaging for butter is a 1 pound box, with four individually wrapped sticks. Each stick is 1/2 cup = 4 ounces. (This is an example of something has the same number of ounces by weight and by volume -- not always the case.)

Yes, 4 ounces (1/2 cup). Sorry for being inexact.

Pretty sure they are 1/2 cup sticks as that is a standard measure