The Metric Units Of Mass (g, kg and others)

5 kilograms scale

If you are not familiar with the metric system, you can find it hard to answer what is the metric unit for mass. But we are here to help! In this article we’re going to give you a little insight into the mass metric unit system, how they use it, and which one they use the more often. Because you guessed it, there are more than one mass units in the metric system.

The Metric Mass Base Unit

The metric system, as any other measurement system, has several units for mass. It is still a structure that’s very easy to understand, see below.

But there is one special unit that is called a base unit in the SI system. (SI is the abbreviation of the official French name of the metric system, International System of Units.) It is called a base unit because all other metric mass units derive from this unit, as we’ll discuss it later.

The metric base unit of mass is the kilogram, often abbreviated as kg.

You can use either kilogram or kg, but kg is more often used as it is simply a shorter form. Kg is also pronounced “kilogram”. “Kilo” is also a very popular form in everyday speech for the kg in almost every language.

It is also one of the two most often used mass units, alongside with it’s little sibling, the gram (or g). More on this later.

How Much Is A Kilogram?

A kilogram is a mass unit that is roughly equal to 2 pounds. It is in fact 2.205 pounds, but I figure it’s easier to visualize one kilogram as being roughly 2 pounds, and you are not far from the truth.

One kilogram is also roughly 35 ounces or 0.15 stones. Please note that all these numbers are rounded.

To put it into another prospective, a 165 pound person is about 75 kilograms, 180 pounds are 82 kg and 200 pounds 90 kg.

Second Most Popular Metric Mass Unit – The Gram

Interestingly the prefix “kilo” in the kilogram means 1000, so it’s basically 1000 grams. Consequently the gram, often abbreviated as g and another very popular metric mass unit, is 1/1000 part of a kg. (It is interesting because even if a kg means 1000 g, the kg is the base unit from which the gram is derived.)

One gram is a very small mass quantity, virtually undetectable by your human senses. It is roughly 1/30 part of an ounce. So if you put one gram of anything in your hand, chance are you won’t notice it by its weight. Still it is a very popular metric mass unit because you can express basically any weight in grams that’s used in an everyday situation and it’s below a kilogram.

Just to give you a few examples, you can buy 100 grams of cheese (roughly 3.5 oz) or 500 grams of tomatoes (a little more than a pound). But it is extremely useful for more precise everyday situations, as you can measure out e. g. 585 grams of flour (or any other quantity), if a recipe calls for that. This would be 20.6353 ounces, virtually unmeasurable. Yes, metric countries use weight for cooking, and it gives much more precise and consistent results.

Other Metric Mass Units

The beauty of the metric system is that you can take any base unit (kilogram in case of mass, but the word gram in this context), and prepend so called prefixes and get another metric mass unit. Such is how kilogram is derived from grams, kilo meaning 1000, so one kilogram meaning literally and technically a thousand grams.

And this is not only an exceptionally easy to follow naming convention, but it makes the metric system also equally easy to use in calculations. As an example, milli (as a prefix) means 1/1000 part, therefore one milligram is 1/1000 part of a gram. So if you want to measure a mass smaller than a gram, just switch to milligrams and multiply everything by 1000. Something that weighs 0.1 grams would be 0.1*1000 = 100 milligrams.

One interesting metric mass unit though, that seems to escape this nomenclature, is the tonne. It doesn’t have the word gram in its name, but it’s still very often used in metric countries. One metric tonne weighs a thousand kilograms, approximately the same as an imperial tonne or a US tonne. Technically, following the metric naming convention, a tonne is a megagram (or Mg for short), but I’ve never actually heard anyone using this word.

Mass Or Weight

People are often searching for the metric unit for weight (instead of mass), and the answer is basically the same that we’ve presented in this article.

In short, the scientific term is the mass, which means the amount of matter of an object, now matter where you measure it. So 1 kilogram would be 1 kilogram here on Earth, on the Moon or even in space.

Weight on the other hand is the mass multiplied by the gravitational field strength. So the weight basically means how much a given mass of matter weighs because it is attracted by gravitational force. Consequently the weight of the same object is different based on where it’s weighed. One kilogram on Earth would be considered the same weight (one kilogram, though this is scientifically not accurate), but only 16% of that on the Moon.

In everyday life we use weight and mass interchangeably. We usually measure the weight, and not the mass, of any substance with a scale, except for the balance-type weighing scale. We still use both the words mass and weight for the result. Also we use the mass metric units to define the weight of something. Scientifically not accurate, but still OK in everyday life as we are measuring everything on Earth. So the answer to the question what is the metric unit for weight is the same that the answer to the question about the metric unit of mass.

I know it’s getting complicated, if you are more interested in this matter, click on the link and read the Wikipedia article about mass vs. weight.

List Of Metric Mass Units

To wrap up, we compiled this table with (almost) all of the metric mass units from smallest to largest and with a roughly estimate to understand how much each weighs.

Metric Mass UnitShort SymbolUsageEquals ToRough Estimate
picogrampgOnly in scientific applications10−12 gToo small for other systems
nanogramngOnly in scientific applications10−9 gToo small for other systems
microgramµgOnly in scientific applications10−6 gToo small for other systems
milligrammgScience, medicine (drugs)10−3 gToo small for other systems
centigramcgNot very often10−2 gToo small for other systems
decigramdgNot very often10−1 gToo small for other systems
gramgEveryday life, science10−3 kg1/30 of an ounce
decagramdag or dkgIn some countries in everyday life10 g1/3 of an ounce
hectogramhgNot very often100 g3.5 ounces
kilogramkgEveryday life, science1000 g2.2 pounds
TonnetEveryday life1000 kgA tonne

Mass Metric Unit Q&A

  • The basic unit of mass in the metric system is the kilogram.
  • The basic metric unit of weight is the kilogram.
  • The symbol for the metric unit used to measure mass is kg.
  • Another unit of mass in the metric system is the gram, though not a basic unit.
  • The abbreviated form of gram is g.
  • One gram is exactly one thousands part of one kilogram.