Weight unit list and detailed explanation


The unit of weight (mass) is used around the world to express the amount of an object, but the units used vary depending on region and context.

Below is a list of commonly used weight units.


International System of Units (SI)

  • kilogram (kg)
    • The basic unit of mass in the International System of Units (SI). 1 kilogram is equal to approximately 2.20462 pounds.
  • Gram (g)
    • 1/1000th of a kilogram. Suitable for measuring the weight of lightweight objects.
  • ton (t)
    • 1000 times the kilogram. Used to measure heavy objects or large amounts of material.


Anglo-American unit system

  • Pound (lb)
    • A unit of mass commonly used in the Anglo-American system of units. 1 pound is equal to approximately 0.453592 kilograms.
  • ounce (oz)
    • 1/16th of a pound. It is mainly used in America to measure the weight of food.
  • stone (st)
    • A unit of measurement used in the United Kingdom, one stone is equivalent to 14 pounds, or approximately 6.35029 kilograms.


Japanese units

  • Momme
    • A traditional Japanese unit of weight. 1 momme is equivalent to approximately 3.75 grams.
  • Kan
    • One kan is equivalent to 1000 momme, or about 3.75 kilograms.


ancient unit

  • talent
    • A unit of weight used in ancient Greece and Rome. Its weight varies depending on the region, but it is often estimated to be around 26 kilograms.


Other units

  • carat (ct)
    • A unit used to express the weight of jewelry. 1 carat is equivalent to 200 milligrams.
  • grain (gr)
    • 1 grain is approximately 0.0648 grams. Used in pharmacy and for weighing ammunition.


As you can see, there are a wide variety of units for expressing weight (mass), and their use varies greatly depending on culture and purpose. In everyday life, kilograms and pounds are the most commonly used units, and in scientific contexts, the kilogram is widely used as an international standard.

Next, we will explain each unit of weight in detail.






kilogram (kg)


The kilogram (kg) is a unit of mass and one of the basic units in the International System of Units (SI).

This unit is widely used in science, industry, commerce and daily life all over the world.


definition of kilogram

As of May 20, 2019, the definition of the kilogram is based on Planck’s constant.

This is due to an international agreement to change the kilogram to something that does not rely on physical artifacts.

With this change, the kilogram was defined on a more stable basis, allowing for more precise measurements.

Planck’s constant ℎ  is defined exactly as 6.62607015 × 10−34  joule seconds (J s), and is used to redefine the kilogram.


The importance of kilograms

The kilogram is the basic unit for measuring the mass of matter and is essential in scientific measurements.

It is used in chemistry to measure the amount of a substance, in industry to determine the mass of a product, and in commerce to weigh goods.

The kilogram is also used in daily life as a unit for measuring the weight of food.


Example of using kilograms

  • Scientific research : Used to accurately measure the mass of substances and balance chemical reactions.
  • Industrial products : Measures the mass of products and is used as a quality control standard.
  • Commercial transactions : Used to measure the weight of goods and determine prices.
  • Daily life : It is used as a standard for selling by weight when purchasing groceries, and when measuring the amount of ingredients for cooking.


History of the kilogram

The definition of the kilogram has gone through several changes historically. In the past, the standard was a platinum-iridium alloy cylinder called the “International Prototype Kilogram” kept in Paris.

However, this method that relies on physical standards has been pointed out to be problematic because the mass of the prototype may vary slightly.

Changes to the current Planck constant-based definition established a more stable criterion.

The redefinition of the kilogram reflects advances in science and technology and allows for more accurate and reproducible measurements of mass.

This unit is used every day around the world, and its importance will never change.






Gram (g)


Gram (g) is a unit of mass and is equivalent to 1/1000 of a kilogram (kg) in the International System of Units (SI).

Since the kilogram is the basic unit of mass, the gram is a derived unit.

It is an important unit used in a wide range of fields such as daily life, science, medicine, and the food industry.


Gram definition and history

The concept of the gram was established in France in 1795 when the metric system was introduced. Originally, 1 gram was defined as the mass of 1 cubic centimeter of pure water.

This definition is based on the mass of water at a temperature of 4°C and an atmospheric pressure of 1013.25 hectopascals.

However, the kilogram is now considered the basic SI unit of mass, and the gram is defined as 1/1000th of a kilogram.


Use of grams

Grams are used in many situations in daily life, such as cooking, selling food by weight, measuring reagents in scientific experiments, and calculating dosages for pharmaceuticals.

It is especially useful for measuring the mass of small objects or small amounts of matter. Gram units are also used to indicate nutritional information and intake amounts of ingredients, and are the standard for health management and dietary restrictions.


Relationship between grams and other units

A gram is 1/1000th of a kilogram. Another smaller unit is the milligram (mg), where 1 gram is equivalent to 1000 milligrams.

An even smaller unit is the microgram (μg), where 1 gram is equivalent to 1 million micrograms. These units are used depending on the accuracy and purpose of expressing mass.


Importance of grams

The gram is a very practical unit that is widely used in daily life and scientific fields because of its easy-to-handle size.

Weighing in grams is essential when calculating the nutritional value of food or when accurate mass measurements are required in scientific experiments.

Accurate measurements in grams are also required when formulating pharmaceuticals and calculating chemical reactions.

Gram plays an important role in our lives in invisible ways, and its use will continue to expand as science and technology progress.






ton (t)


A ton (t) is a unit of mass, especially used to express the weight of large amounts of material or objects.

Although not part of the International System of Units (SI), it is often used in conjunction with SI units, and one tonne is equivalent to exactly 1000 kilograms (kg).

This unit is frequently used in large-scale commercial and industrial activities, such as manufactured goods, ships, aircraft, and construction materials.


types of tons

There are mainly types of tons as shown below, but the commonly mentioned “ton” refers to metric tons.

  • Metric ton (public) : 1 metric ton is equivalent to 1000 kilograms.
  • Long ton : Mainly used in the United Kingdom, one long ton is equivalent to 2240 pounds, or approximately 1016 kilograms.
  • Short ton (US ton) : Used in the United States, one short ton is equivalent to 2000 pounds, or approximately 907 kilograms.


ton usage

Tons are widely used in industries that handle large amounts of materials.

For example, the ton unit is used to express the carrying capacity of ships, and in commercial transactions such as construction materials, minerals, and agricultural products.

In the energy industry, tons are also used to indicate the amount of traded fuels such as oil and coal.


The importance of tons

The ton is an essential unit in large-scale commercial and industrial activities.

Using this unit makes it possible to clearly express the weight of large quantities of goods and materials, facilitating smooth business transactions, including international trade.

The use of ton units also allows for accurate weighing and cost evaluation in planning and operations of various industries, such as logistics, manufacturing, and construction.


The ton is an essential unit for handling large amounts of weight and is widely used in various industries around the world.

There are different types: metric ton, long ton, and short ton, so it is important to be clear about which ton we are referring to in an international context.

Ton allows the weight of large quantities of materials and products to be consistently measured and understood, ensuring efficiency and accuracy throughout industry.






Pound (lb)


Pound (symbol: lb) is a unit of mass (weight), especially widely used in the Anglo-American system of units.

Its origins date back to ancient Rome and are derived from the Latin word “libra”.

Libra means balance and represents the weight that maintains balance.

In modern times, 1 pound equals exactly 0.45359237 kilograms (kg), and this conversion is the standard used in international trade and science.



Use of pounds

The pound is a unit of measurement commonly used in several countries, including the United States and the United Kingdom.

We see it in many situations in our lives, such as food weight displays, people’s weight, and the mass of sports equipment.

It is also used commercially to indicate the weight of cargo, particularly in the United Kingdom and the United States, where it is commonly expressed in pounds.


Relationship between pounds and other units

  • Relationship to kilograms : 1 pound is equal to 0.45359237 kilograms. This conversion rate is internationally recognized and is used to convert between the Anglo-American system of units and the metric system (International System of Units).
  • Relationship to ounces : 1 pound is equal to 16 ounces (oz). Ounce is a smaller unit of mass and is used to subdivide pounds.


The importance of pounds

The pound plays an important role in a wide range of fields, from daily life to industry, especially in countries that use the Anglo-American system of units.

International trade and scientific research maintain compatibility with the metric system of units through conversion to kilograms.

In this way, the pound is a globally recognized unit that contributes to communication and transactions in the international community.


The pound has a long history as a unit of mass and is still widely used in modern times, especially in Britain and the United States.

Its conversion rate is clearly defined and also plays an important role in international trade and scientific research.

The conversion between pounds and kilograms serves as a bridge between different unit systems, promoting understanding and cooperation around the world.






ounce (oz)


definition and history

The ounce (symbol: oz) is a unit used to measure weight, especially in Anglo-American countries.

Its origin goes back to ancient times, and is said to come from the unit “uncia” used during the Roman Empire.

This referred to one-twelfth of the Roman weight unit “libra” (approximately 454 grams).


Fields of use

Ounces are used in everyday life to express the weight of food and to express the amount of precious metals.

In particular, in the United States, ounces are often used to display the weight of common ingredients, and are also commonly used in cooking recipes.

The ounce is also used as the unit for trading precious metals such as gold and silver, and has become the standard unit in international markets.


Unit conversion

Ounces differ from the metric system and must be converted to units such as grams (g) or kilograms (kg).

1 ounce is equal to approximately 28.3495 grams. Therefore, use this conversion value when converting ounces to grams or kilograms.



Points to note when using ounces

When using ounces, it is necessary to understand the units depending on the region and field.

In particular, the definition of an ounce may differ slightly between the United States and the United Kingdom, so accurate conversion is required for international transactions and information exchange.

Also, when cooking, it is important to accurately measure the amount of ounces specified in a recipe, and the use of a kitchen scale is recommended to improve cooking accuracy.






stone (st)


Definition and origin

A stone (symbol: st) is a unit of mass primarily used in the United Kingdom.

1 stone is equal to 14 pounds (lb), which is approximately 6.35029 kilograms (kg).

This unit has long been used to measure weight in Britain and Ireland, and is still widely used today, especially when expressing individual weight.


Culture and region used

Stone is a unit found primarily in Great Britain and is not commonly used in the United States or other countries that use metric systems.

Although metric units are increasingly being used in official documents and scientific contexts in the UK, stones are still the preferred way to express weight in everyday conversation.


Stone conversion

When converting stones to other units, especially kilograms and grams in the metric system, we make use of the fact that 1 stone is equal to approximately 6.35029 kilograms.

For example, 10 stone weighs approximately 63.5029 kilograms. By converting in this way, it becomes easier to understand in international communication.


Considerations in the use of stones

Stone is a unit rooted in the culture and customs of a particular region, and its use is closely related to the physical senses and traditions of the British people.

The continued use of stones in everyday life, even as the transition to metric systems progresses, reflects people’s long-standing attachment to the units and the deep cultural meaning they hold. However, in an international context, the use of metric units is recommended, so you need to be considerate of your audience’s understanding and unit system when using stones.







definition and history

Monme is a unit of mass unique to Japan, and is based on the traditional unit system “Shakanho” established in the Edo period.

1 momme is equivalent to approximately 3.75 grams in modern units. It was originally a unit used to measure the weight of coins, especially silver coins.


Culture and region used

Momme is still used in modern Japan, especially when weighing valuable items such as pearls and jewelry.

However, since the metric system has been adopted as the standard unit system in Japan, there are fewer opportunities to use momme in daily life.

It continues to be valued in traditional crafts and historical contexts.


Momme conversion

When converting momme to other units, especially grams in the metric system, we base our calculations on the fact that 1 momme is equal to approximately 3.75 grams.

By using this conversion ratio, it is possible to understand the weight expressed in momme in internationally accepted units.

For example, 100 momme is equivalent to approximately 375 grams.


Thoughts on the use of momme

Momme is a unit that symbolizes Japanese tradition and history, and its continued use in certain fields is a sign of cultural inheritance and respect.

However, in today’s increasingly globalized society, the standardization of metric systems is progressing, and the use of traditional units, including momme, has become limited.

In this context, when using Momme, understanding the cultural background and conversion method will contribute to promoting mutual understanding.








Definition and origin

Kan is a traditional Japanese unit of mass, and is the unit of weight in Shakanho.

One kan is equivalent to approximately 3.75 kilograms (or approximately 8.27 pounds) and is said to be equivalent to 1000 monme.

The kan was mainly used in commercial transactions and in weighing goods, and played an especially important role in the trade of food products such as rice and fish.


Culture and region used

Although kan is hardly used in everyday life today, its remnants can be seen in traditional industry and culture.

Particularly in Japan’s fishing and agricultural fields, kan is still sometimes used as a notation as a traditional practice.

It is also sometimes used to express the weight of tools in fields such as martial arts.


Kan conversion

When converting kan into modern units, it is important to note that 1 kan is equivalent to approximately 3.75 kilograms.

Based on this conversion rate, it is possible to convert weight expressed in kan to International System of Units (SI) such as grams and kilograms.

For example, 10 kan is equivalent to approximately 37.5 kg.


Thoughts on the use of kan

Kan is a unit rooted in Japanese history and culture, and its use provides an interesting aspect to understanding Japanese tradition and history.

Although metric systems are widespread in modern society, it is important from the perspective of preserving and transmitting cultural heritage that traditional units such as kan are still used in some areas.

However, in order to promote international understanding, it is necessary to translate and understand these traditional units into a metric system.








Definition and origin

A talent is an ancient unit of weight or money, and its weight varied greatly depending on the region and time period in which it was used.

Used by ancient Greek, Roman, and Middle Eastern cultures, this unit most commonly ranged from about 26 kilograms to about 60 kilograms, although its exact weight was determined by specific locations and periods. It has changed depending on.


Culture and region used

Talents were used in ancient civilizations primarily in the Mediterranean region.

This unit was widely used in economic activities and commerce at the time, and played an especially important role in trading large quantities of goods and valuables.

Talents also functioned as monetary units, and were sometimes used as a means of exchange of value by referring to specific weights of gold or silver.


Talent conversion

Converting the weight of a talent to modern units of measurement is difficult because different ancient regions had different definitions of talent.

Generally speaking, one talent is considered to range from approximately 26 kilograms to approximately 60 kilograms, but determining the exact equivalent value in ancient Greece and ancient Rome requires an understanding of the specific historical context. there is.


Thoughts on using talents

Talents are very interesting units for understanding international trade and monetary systems in ancient economies and cultures.

The use of this unit provides important clues about the interactions between ancient civilizations and how trade and economic activity took place.

Although it has no direct use in modern times, its importance in historical contexts provides valuable insight into our understanding of ancient commercial and monetary systems.

Talent is a fascinating subject for study in learning how people in the past conducted economic activities and measured value.







carat (ct)



A carat (ct) is a unit used to measure the weight of gemstones and precious metals.

One carat is exactly equal to 0.2 grams (200 milligrams).

This unit is widely used, especially to indicate the weight of diamonds and other precious gemstones.


history and origin

The name carat comes from a small seed called “kerathion” that was used in ancient times as a weight standard for gemstones.

This seed had such a consistent weight that it was used as a standard for weighing fine jewelry.

Over time, the carat evolved into a more precise unit of measurement and became an internationally recognized standard.


Use of carat

Carat plays an important role in assessing the value of a gemstone.

The value of a gemstone is determined by several factors, including its size (carat weight), color, clarity, and polish quality, and carat weight is one of the most fundamental indicators of these factors.

Especially when purchasing diamonds, the carat weight is one of the main factors that determines the price.


Importance of Carat

Carat weight measurement is a very precise operation in the jewelry industry. By using this unit, it is possible to evaluate the value of gemstones fairly and transparently.

Buyers can compare the size and price of gemstones based on carat weight, making the purchasing selection process more clear.

The carat unit accurately conveys the quality of a gemstone and helps consumers make informed purchasing decisions.

As such, the carat is an important tool for measuring the beauty and value of gemstones, and is an essential standard unit of measurement in the jewelry industry.






grain (gr)



A grain (gr) is a unit of mass and is used especially in the fields of pharmacy, gemology, and ammunition.

1 grain is equal to approximately 0.06479891 grams. This unit comes from the English word “grain” and was based on the average weight of wheat or barley seeds since ancient times.


History and uses

A grain is one of the units of mass that has been used for a very long time. Originally based on the weight of seeds used in agriculture, over time it was applied to mass measurements in a broader range of applications.

In modern times, it is primarily used in pharmacy to measure the weight of drugs, in gemology to measure the weight of small gemstones and precious metals, and especially to express the weight of ammunition used in shooting and hunting.


Importance of grain

Grain units are valued for their accuracy, especially in fields that require precision.

For example, pharmacists use grain units to ensure accurate drug compounding, and jewelers utilize grain units to accurately measure the weight of small jewelry.

Additionally, in shooting sports and hunting, expressing the weight of ammunition in grains allows for more accurate trajectory prediction and performance evaluation.


The modern role of grain

Grains have a very small value compared to other units of mass, making them very suitable for detailed weight measurements.

The use of this unit is essential to ensure accuracy and consistency in many professional fields where precision measurements are required.

Therefore, grains retain their status as an important mass unit that is widely used even today.

This unit allows experts to identify even the smallest differences, allowing them to work more precisely.




List of weight units unique to each country around the world



Finally, we will introduce a list of units of weight that are uniquely used (used) in different countries around the world.

If you are interested, please refer to it.




  • Japan
    • Momme : Approximately 3.75 grams
    • Kan : Approximately 3.75 kilograms (equivalent to 1000 momme)
  • India
    • Thora : Approximately 11.66 grams (mainly used for weight of gold and silver)
    • Seer : Approximately 933 grams (may vary depending on region)
  • China
    • Gin : Approximately 500 grams
    • Liang : Approximately 50 grams (1/10 of 1 loaf)


middle east

  • Ottoman Empire/Türkiye
    • Oka : approximately 1.28 kilograms (values ​​vary depending on region)



  • England
    • Stone (st) : approximately 6.35 kilograms (equivalent to 14 pounds)
  • Russia
    • Pood : Approximately 16.38 kg



  • Egypt
    • Oka : Approximately 1.25 kg (may differ from Oka in other countries)


ancient unit

  • ancient greece
    • Talent : Approximately 26 kg to approximately 60 kg (varies depending on era and region)
  • ancient rome
    • Libra : approximately 327 grams (origin of the modern pound)



These units were widely used in each region before being replaced by the modern metric system (SI). Today, metric systems still predominate in international trade and scientific contexts, although they are sometimes used for cultural reasons or in traditional commercial transactions.


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