Weight & Mass Converter

Weight vs. Mass: What You Are Actually Converting

In everyday language "weight" and "mass" are used interchangeably, but they are physically different things. Mass is the amount of matter in an object — it stays the same whether you are on Earth, the Moon, or in orbit. Weight is the force gravity exerts on that mass, so it changes with gravity. The kilogram (kg) is the SI base unit of mass. The pound (lb) in the US customary system is technically a unit of force, but in practice it is used as if it were a mass unit. For the purposes of conversion, 1 kg = 2.20462 lbs.

Common Weight Conversion Factors

The most frequently needed conversions:

• 1 kilogram = 2.20462 pounds
• 1 pound = 453.592 grams
• 1 stone = 14 pounds = 6.35029 kg (used for body weight in the UK and Ireland)
• 1 ounce = 28.3495 grams
• 1 metric ton (tonne) = 1,000 kg = 2,204.62 lbs
• 1 US short ton = 2,000 lbs ≈ 907 kg

Practical example: a 70 kg person weighs 70 × 2.20462 = 154.3 lbs, or 154.3 ÷ 14 = 11 stone 0.3 lbs in British usage.

Where Each Unit Is Used

Kilograms and grams are standard everywhere outside the United States for grocery shopping, body weight, and shipping. Pounds and ounces remain common in the US and occasionally in Canada and the UK for informal contexts. Stones are almost exclusively a British and Irish unit for expressing human body weight — you will rarely see them in any other context.

In cooking, ounces are used ambiguously: a recipe may call for 8 oz of flour (a mass measurement) or 8 fl oz of milk (a volume measurement). These are not the same — always check whether a recipe means fluid ounces or weight ounces, especially when converting international recipes.

Milligrams and micrograms appear in pharmaceutical and nutritional contexts: medication doses, vitamin amounts on supplement labels, and nutrient data on food packaging. A single gram contains 1,000 milligrams, so converting between them is just a matter of moving the decimal point.