Poids et masse

About Weight Conversion

Weight (or more precisely, mass) is one of the most frequently converted measurements in daily life. Whether you're following a recipe, tracking fitness goals, shipping packages, or comparing product specifications, understanding weight conversions is essential. Mass is a fundamental property of matter—the amount of substance in an object—while weight technically refers to the gravitational force on that mass.

The metric system uses kilograms and grams, which are standard in science and most countries worldwide. The imperial system relies on pounds and ounces, primarily used in the United States. The UK uniquely uses stones for body weight, a tradition dating back centuries. Our converter handles all common weight units with precision, ensuring accurate results for any application.

Note: While "weight" and "mass" are technically different (weight depends on gravity—you'd weigh less on the Moon but have the same mass), they're used interchangeably in everyday contexts on Earth where gravity is constant.

Common Weight Conversions

Weight Unit Reference

Milligram (mg) – Used for medications, vitamins, and precise scientific measurements. 1,000 mg = 1 gram. Common in pharmacology and nutrition labeling for micronutrients.

Gram (g) – Common for food nutrition labels, cooking ingredients, and small items. The base metric unit divided by 1,000 equals 1 kg. Standard in scientific work worldwide.

Kilogram (kg) – The SI base unit of mass, used worldwide for body weight, groceries, and shipping. Since 2019, defined by the Planck constant rather than a physical artifact, ensuring perfect stability.

Metric Ton (t) – Used for large quantities like vehicles, cargo, and industrial materials. 1 metric ton = 1,000 kg = 2,204.6 pounds. Standard in international shipping and trade.

Ounce (oz) – Imperial unit for food portions, small packages, and precious metals. 16 avoirdupois ounces = 1 pound. Troy ounces (31.1 g) are used for gold and silver, slightly heavier than avoirdupois ounces (28.35 g).

Pound (lb) – Primary unit in the US for body weight, groceries, and shipping. 1 pound = 453.592 grams exactly. The avoirdupois pound is the standard; troy pounds (for precious metals) equal only 12 troy ounces.

Stone (st) – British unit for body weight, still widely used in UK and Ireland. 1 stone = 14 pounds = 6.35 kg. Originated from actual stones used as counterweights in markets.

US Ton (short ton) – Used in the United States for heavy cargo and commodities. 1 US ton = 2,000 pounds ≈ 907 kg. Also called "short ton" to distinguish from the UK "long ton" (2,240 pounds).

Learn More

Explore our in-depth guides on this topic:

• How to Convert Ounces to Grams
• Pounds vs Kilograms: A Complete Guide
• Cooking Weights: A Guide to Grams, Ounces, and Cups