Metric System

The metric system is based on powers of 10, making conversions straightforward:

• Microgram (µg): 0.000001 grams, used in pharmaceutical and scientific contexts
• Milligram (mg): 0.001 grams, commonly used in medicine and nutrition
• Gram (g): Base unit of mass in the metric system
• Kilogram (kg): 1,000 grams, standard unit for everyday use
• Metric Ton (tonne): 1,000 kilograms, used for large quantities

Imperial System

The imperial system uses different conversion ratios:

• Ounce (oz): 28.35 grams, used for small weights
• Pound (lb): 16 ounces or 453.59 grams, common in the US for everyday use
• Stone (st): 14 pounds, commonly used in the UK for body weight
• Short Ton (US): 2,000 pounds, used in the US for large weights
• Long Ton (UK): 2,240 pounds, traditionally used in the UK

Other Specialized Units

• Carat (ct): 0.2 grams, used for gemstones and jewelry
• Troy Ounce: 31.1 grams, used for precious metals
• Slug: Physics unit equal to 14.59 kg, based on force
• Atomic Mass Unit (amu): Approximately 1.66 × 10^-24 grams, used in atomic physics
• Solar Mass: 1.989 × 10^30 kg, used in astronomy

Weight vs. Mass

Although often used interchangeably in everyday language:

• Mass: A measure of the amount of matter in an object (kg, g)
• Weight: The force exerted on an object due to gravity (Newtons)

On Earth, an object's weight is proportional to its mass, which is why we often use mass units to describe "weight".