butter volume weight chart:
Cup Gram Ounce Pound Kilogram Tablespoon Teaspoon
stick 1/2 113.4g 4 oz 0.25 lb 0.113Kg 8 24
half stick 1/4 56.7g 2 oz 0.125 lb 0.056Kg 4 12
double stick 1 226.8g 8 oz 0.5 lb 0.226Kg 16 48
tablespoon 3/50 14.2g 0.5 oz 0.03 lb 0.014Kg 1 3
teaspoon 1/50 4.7g 0.16 oz 0.01 lb 0.004Kg 0.33 1

Source:
http://www.traditionaloven.com/conversions_of_measures/butter_converter.html

I have often been puzzled by American recipes calling for a stick of butter,  did some searches today and came up with the above.

KD

Simple way to look at this that I have always done is a stick of butter is half a pound on the old scale or 225 grms on the new one. :)