Converting weight units: geun, don, pounds and ounces

Mass and weight are used interchangeably

Strictly speaking, the kilogram is a unit of mass, and weight is the force gravity exerts on that mass. On the Moon your mass stays the same while the reading on a scale drops. In everyday life on Earth, though, there is rarely any need to separate the two, and scales are calibrated to show mass based on Earth's gravity. This article follows everyday usage and calls it weight. For reference, the scientific unit of force is the newton, and one kilogram-force is defined as exactly 9.80665 newtons under standard gravity.

Don and nyang, the units for gold

The don is a traditional Korean unit of weight: 1 don is 3.75 g. Ten don make 1 nyang (37.5 g), and 1,000 don make 1 gwan (3.75 kg). People still commonly talk about gold rings or gold prices in don. Since 2007, however, Korea has required legal metric units, so official transactions and labels use grams and the don survives by custom. When buying or selling gold, even if the conversation is in don, it is safer to confirm the actual weight in grams and the purity. The same one don contains different amounts of gold depending on purity.

A geun of meat versus a geun of vegetables

The geun is confusing because its weight depends on what is being sold. For meat, 1 geun is generally counted as 600 g, while for vegetables and fruit it has customarily been 375 g, which is one tenth of a gwan. So the same one geun differs by 225 g between the butcher and the greengrocer. Most goods are now priced by the gram, but when geun comes up at a market or in conversation, adjust the basis to the item. If the exact weight matters for a purchase, confirm it in grams.

Exact values for pounds and ounces

Pounds and ounces turn up constantly in American and British sources. Since an international agreement in 1959, the pound has been defined exactly in terms of the kilogram, so the conversions need no approximation.

• 1 pound = 0.45359237 kg (exact) ≈ 453.6 g
• 1 ounce = 1/16 pound = 28.349523125 g
• 1 kg ≈ 2.2046 pounds
• 1 stone = 14 pounds ≈ 6.35 kg

Same name, different ounce

Several different units are called an ounce, so take care. The ounce used for food and everyday items is the roughly 28.35 g one above. Precious metals such as gold and silver use the troy ounce, which is exactly 31.1034768 g, about 10% heavier than the ordinary ounce. When international gold prices are quoted per ounce, that usually means the troy ounce, which is about 8.29 don. And the fluid ounce printed on drink containers is a unit of volume, not weight. Whenever you see ounces, first check whether it is weight or volume and whether it is the precious-metal ounce.

Even the ton is not one unit

The ton used for large weights also varies by region. In metric countries, Korea included, a tonne is 1,000 kg. The short ton common in the United States is 2,000 pounds, about 907 kg, and the British long ton is 2,240 pounds, about 1,016 kg. The same one ton can differ by more than 100 kg. When reading cargo weights or load capacities in American sources, check which ton is meant, and convert to kilograms when you copy the numbers. Ship tonnage is yet another concept, as it sometimes refers to volume rather than weight.

Everyday conversions

Working out the numbers you meet most often saves time. Decimals are rounded.

• One don of gold = 3.75 g; ten don = 37.5 g
• One geun of meat = 600 g ≈ 1.32 pounds
• 1 pound ≈ 0.76 geun (600 g basis)
• A body weight of 150 pounds ≈ 68.0 kg
• 16 ounces = 1 pound ≈ 453.6 g

Common mistakes

Most weight conversion errors come from mixing units that share a name but differ in value. When using a scale, remember to zero it to subtract the container, and for things where small differences matter, such as precious metals or medicine, use a scale with a stated precision.

• Counting a geun of vegetables as 600 g, as for meat
• Converting a troy-ounce gold price using the ordinary ounce
• Reading a ton in an American source as 1,000 kg
• Treating the fluid ounce, a unit of volume, as weight