Convert from pound to tonne

Unit Definition (pound)
The pound is a traditional unit of mass or weight. The Romans used a pound (the libra pondo, "pound of weight") divided into 12 ounces. All the countries of western Europe used similar units, divided into 12 or 16 ounces, until the advent of the metric system. 12-ounce pounds were common in Italy and southern France, but in Spain and northern Europe 16-ounce pounds became the norm. The word libra is used for this unit in Italy, Spain, and Portugal; in France it is called the livre. Further north, the Latin word pondo ("weight") is the origin of the names of the English pound, Dutch pond, Danish pund, German pfund, and Russian funt. In England, two different "pound" units became standard. The unit now in general use in the United States is the avoirdupois pound, so-called from a French phrase avoir du poids, literally "goods of weight," indicating simply that the goods were being sold by weight rather than by volume or by the piece. The avoirdupois pound is divided into 16 ounces. By international agreement, one avoirdupois pound is equal to exactly 453.592 37 grams; this is exactly 175/144 = 1.215 28 troy pounds.

Unit Definition (tonne)
The tonne is a metric unit of mass equal to 1000 kilograms or approximately 2204.623 pounds avoirdupois. The SI uses this French spelling for the metric ton to distinguish it clearly from the long and short tons of customary English usage. Large masses are often stated as multiples of the tonne, although technically the SI requires that masses be stated as multiples of the gram. Thus a mass of 10³ tonnes = 10⁶ kg = 10⁹ g is often called 1 kilotonne (kt) instead of 1 gigagram. In the United States, the Department of Commerce recommends that the tonne be called the metric ton.