Weight converter
Convert weight and mass units instantly — kilograms, pounds, ounces, grams, stones, and more.
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Common weight units
Kilogram (kg)
Definition: The kilogram (symbol: kg) is the SI base unit of mass. Since 2019, it is defined by fixing the numerical value of the Planck constant to exactly 6.626 070 15 × 10^-34 joule-seconds, replacing the previous definition based on a physical platinum-iridium cylinder.
History/origin: The kilogram was originally defined in 1795 as the mass of one liter of water at 4 °C. In 1889 it was redefined as the mass of the International Prototype of the Kilogram (IPK), a physical artifact kept in France. The 2019 redefinition tied it to a fundamental physical constant instead.
Current use: The kilogram is the standard unit of mass in virtually every country. It is used in commerce, science, food packaging, and health. Body weight, food portions, and shipping weights are routinely expressed in kilograms worldwide.
Pound (lb)
Definition: A pound (symbol: lb) is a unit of mass in the imperial and US customary systems. The international avoirdupois pound is defined as exactly 0.45359237 kilograms. There are 16 ounces in a pound and 2,000 pounds in a short ton.
History/origin: The pound traces its origins to the Roman "libra pondo" (a pound by weight), from which both its name and symbol derive. Various versions of the pound existed across different regions and eras until the avoirdupois pound was standardized internationally in 1959.
Current use: The pound is the primary unit of body weight in the United States and is also used in the UK alongside kilograms. It is common in food labeling, aviation, and general commerce in countries that have not fully adopted the metric system.
Gram (g)
Definition: A gram (symbol: g) is one thousandth of a kilogram (1 g = 0.001 kg). It is a unit of mass in the SI metric system and the most practical unit for measuring small quantities.
History/origin: The gram was originally defined in 1795 as the mass of one cubic centimeter of water at 4 °C, the same basis as the early kilogram definition, just scaled down by a factor of 1,000.
Current use: Grams are widely used in food nutrition labels, cooking recipes, pharmaceutical doses, and jewellery. Most food packaging worldwide lists weight in grams or kilograms.
Ounce (oz)
Definition: An ounce (symbol: oz) is a unit of mass equal to 1/16 of a pound, or approximately 28.3495 grams. The international avoirdupois ounce has been the standard since 1959.
History/origin: The ounce has Roman roots. The Roman "uncia" was 1/12 of a Roman pound. Over time the number of ounces per pound settled at 16 in the avoirdupois system used for most everyday goods.
Current use: Ounces are commonly used in the United States for food portions, postal weights, and product packaging. The troy ounce (31.1 g) is a separate unit used specifically for precious metals like gold and silver.
Weight conversion table
| From | To | Result |
|---|---|---|
| 1 Kilogram (kg) | Pounds (lb) | 2.2046 lb |
| 1 Pound (lb) | Kilograms (kg) | 0.4536 kg |
| 1 Gram (g) | Ounces (oz) | 0.0353 oz |
| 1 Ounce (oz) | Grams (g) | 28.3495 g |
| 1 Kilogram (kg) | Grams (g) | 1000 g |
| 1 Pound (lb) | Ounces (oz) | 16 oz |
| 1 Metric ton (t) | Kilograms (kg) | 1000 kg |
| 1 Metric ton (t) | Pounds (lb) | 2204.6 lb |
| 1 Stone (st) | Kilograms (kg) | 6.3503 kg |
| 1 Stone (st) | Pounds (lb) | 14 lb |
How to convert weight units
Weight conversions use fixed multiplication factors. Multiply your value by the conversion factor to get the result in the target unit.
Kilograms to pounds
pounds = kilograms × 2.2046226218
Example: 70 kg = 70 × 2.2046226218 = 154.32 lb
Pounds to kilograms
kilograms = pounds × 0.45359237
Example: 150 lb = 150 × 0.45359237 = 68.04 kg
Grams to ounces
ounces = grams × 0.0352739619
Example: 500 g = 500 × 0.0352739619 = 17.637 oz
Frequently asked questions
How do I convert kilograms to pounds?
Multiply the kilogram value by 2.2046. For example, 70 kg = 70 × 2.2046 = 154.3 lbs. To convert pounds to kilograms, multiply by 0.4536. A quick mental estimate: multiply kg by 2.2 for a close approximation — 80 kg ≈ 176 lbs.
How many pounds are in a kilogram?
One kilogram equals approximately 2.2046 pounds. One pound equals exactly 0.45359237 kilograms. This conversion is most commonly needed for body weight (US uses pounds, most of the world uses kilograms) and for food and ingredient quantities in imported recipes.
How do I convert pounds to stones?
Divide the pound value by 14. For example, 154 lbs ÷ 14 = 11 stone. To get stones and pounds, take the whole number of stones and the remainder is the pounds. For example, 160 lbs = 11 stone 6 lbs (11 × 14 = 154, 160 − 154 = 6). The stone unit is used almost exclusively in the UK and Ireland for body weight.
How many grams are in an ounce?
One avoirdupois ounce equals 28.3495 grams. One gram equals approximately 0.03527 ounces. This conversion is commonly needed when following US recipes that list ingredients in ounces while working with a metric kitchen scale. Note: the troy ounce (used for precious metals) is different — it equals 31.1 grams.
How do I convert body weight from kg to stones and pounds?
First multiply kg by 2.2046 to get total pounds. Then divide by 14 to get stones, with the remainder as pounds. Example: 75 kg × 2.2046 = 165.3 lbs. 165.3 ÷ 14 = 11 stone 9.3 lbs. Common reference: 70 kg = 11 st 0 lb, 80 kg = 12 st 8 lb, 90 kg = 14 st 2 lb.
What is the difference between a metric ton and a US ton?
A metric ton (tonne) equals exactly 1,000 kilograms or approximately 2,204.6 pounds. A US short ton equals 2,000 pounds or approximately 907.2 kilograms. A UK long ton equals 2,240 pounds or approximately 1,016 kilograms. The metric tonne is the international standard in science and trade; the short ton is used in the US for commodities.
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