Pounds to Kilograms conversion.

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Lb Kg
How many Pounds in 21 Kilograms? How to convert 21 Kg to Lb?

The simple answer is: 9.53

Use our Lb to Kg converter to understand:

How many Kg are in 21 Lb?

21 Pounds is equal to how many Kilograms

How to recalculate 21 Pounds to Kilograms?

What is the formula to convert 21 from Lb to Kg

Pounds to Kilograms formula: [Kg] = [Lb] * 0.453592

The final formula to convert 21 Lb to Kg is: [Lb] = 21 * 0.453592 = 9.53

Kilogram is the SI unit of mass. Mass is defined as the tendency of objects at rest to remain so unless acted upon by a force. Kilogram came from the French word kilogrammes. It was incorporated into the French law in the decree of 18 germinal of 1795. In the United Kingdom, its use began in early 1797.

What is it?

A kg is the base unit of mass in the International System of Units (SI). It may also be noted as the weight of volume of pure water equal to the cube of the hundredth part meter in the temperature of melting ice.

Background story

Back in the olden days, what defined relationships among countries was their trade routes and war of course. Trade was something that all sides engaged in because they could not produce everything they needed in their own country. As is with most dealings there were the fears of theft and of fraud.

France, Britain and the other northern Europe countries had to find a system of measurement that was standard and undisputed. There were various people commissioned to look unto this and come up with a sustainable unit.

The earliest units to be discovered was the gram. The limitation of the gram lay in the fact that most items weighed more than a gram. And a centimeter wasn’t really a unit of mass. In 1795 king Louis XII commissioned various scientists to look into something that could be standard.

Two scientists Louis Lefevre and an Italian were the first people to come up with a kilogram as the relative weight of water at its maximum density which at the time was 4 degrees. Over the years the kilogram was compared to the mass of melting water and it was eventually incorporated into the standard units of measurements.


The magnitude of the kilogram has been defined as the mass of an object called the international prototype of kilogram. The original IPK is made of platinum alloy and stored in a place near Paris.There are various sisters to the original prototype found in different parts of the world.

The pound

The pound is a useful unit of mass as well. It is most common in the imperial and United States customary law. There are different kinds of pounds with the most common one being the avoirdupois pound.

The avoirdupois pound is abbreviated as lb. which claims its roots back to the roman culture: Libra. Libra refers to a measure of scale just as you knew it from astrological sign.

One pound is basically 0.45359237kgs. Metrically, it is approximately 500 grams in weight.

Background story

The original story of the pond dates back to trade and commerce done in the prehistoric area. Arabs are credited as to being the first’s foreigners to scout trade routes into both Africa and Europe. There was no standard measure of weight or currency at the time. Trade was either done on the basis of need-want or through the exchange of gold and silver coins.

This, of course created a lot of opportunities for fraudulent deals. The need therefore arose of finding a single unit of measurement by which all the good could be graded.

The realist foam of the pound was the merchant pound, this however was adopted by many different countries which then gave rise to the different kinds of pounds:

  • French liver
  • Troy pounds
  • Tower pounds
  • Merchant pounds
  • London pounds
  • Russian pound
  • Scandinavian scalped
  • Jersey pound
  • Byzantine lira
  • French liver

It is important to note that pounds are use in weaponry to grade firing pores of canons.

Pounds are however only used in the informal sense unless they are converted to grams because the European Union does not recognize it is a sanctioned weight for trade.

How to convert lbs to kilograms

Considering both are units of standard SI units, the conversion is pretty simple.

  • Know the number of pounds you need to convert.
  • Have a calculator. This formulae has decimal points and may be confusing
  • Divide the pounds by 2.2
  • Better still, there are many only converters that will solve the challenge for you in no time.

    With this knowledge in mind you can comfortably discuss weight and the pound in terms of history. It is also important to note that the pound is not the ounce.

Convert 21 Lb (pounds) to Kg (kilograms)
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