4 tablespoons of butter is how many tablespoons of coconut oil
In almost all contexts, you can substitute these items on equal amounts, by weight or volume, and be well within the tolerance of the recipe.

This is true for almost all baked goods, for example.

If you want to be absolutely accurate, butter is only about 80% fat, and 20% water (this is an approximation), so you would use 4/5 the amount of coconut oil as butter.