Well, I've had several different dimensions of butter sticks in my hometown back in the US, but they were always the same weight, 4oz, with all the tablespoons marked on it.
Some were short and fat, other sticks were long and thin. You could get butter like the UK style, but if you bake with it or cook with it everything is in tablespoons. Generally you'd buy a pound of butter in 4 sticks.