According to the CIA Factbook only Burma (Myanmar), Liberia, and the United States have yet to adopt the International System of Units as their official system of measurement.[2][3] The actual situation, however, is more complicated than the CIA Factbook's listing would suggest.
In the United Kingdom, for example, although metric is the official system for most regulated trading by weight or measure purposes, the pint is the official unit for milk in returnable bottles and for draught beer and cider in British pubs, and miles, yards and feet remain the official units for road signage.
Some sources identify Liberia as metric while reports from Burma suggest that that country is planning to adopt the metric system. However, they all have adopted metric measures to some degree through international trade and standardisation[3] for example, Sierra Leone switched to selling fuel by the litre in May 2011.[4] The United States mandated the acceptance of the metric system in 1866 for commercial and legal proceedings, without displacing their customary units.[5]
-http://en.wikipedia.org/wiki/Metrication