Systems of measurement are one of the cornerstones of human civilization. They allow people from all over the globe to trade on equal terms and to understand the boundaries and categories into which we divide the world through the same eyes.

Countless measurement systems have been used over millennia that have grown and adapted thanks to human innovation, communication, and violent imposition. However, now, there are two main measuring systems used in the world: the metric system and the imperial system.

The metric system is used by the majority of countries and is the international standard. The imperial system is only used by a handful of countries, but given its continued use in full by the USA and in part by the UK, it remains a common and influential system in societies and cultures across the world.

We are going to look at the history of weights and measures and find out the story of how we ended up where we are today.

The earliest recorded systems of measurement that we know of were created between the fourth and third millennia BC by the ancient civilizations in Mesopotamia, the Indus Valley, Egypt, and Elam. Uniform measurement systems are necessary for societies to flourish as they allow for trade, agricultural planning, and the development of construction projects, so it makes sense that the earliest known measurement systems date back to the earliest known civilizations.

Since then, systems of measurement have changed due to advancements in technology and science and have spread due to colonialism, imperialism, and the need for a universal approach to facilitate trade.

Some of the most significant contributions to the history and weights and measurements were made by the Romans. So let's jump in and find out about the measurement of weight and length during ancient times.

How was the weight and length of objects measured during ancient times?

Ancient records from Mesopotamia, Egypt, and the Hebrew Bible show that length was measured by arms, hands, and finger sizes. This meant that there was no standardized system of measurement as every person's body parts are different sizes. Instead, there was a uniform way of measuring length with a degree of variation.

Merchants and traders would have used balancing scales to make weight measurements. Seeds and stones were used for weight standards, so if you wanted to buy something, its worth was measured against its weight. For example, the carob seed was used to measure precious stones and jewelry as there is little discrepancy between carob seed weights. The carob seed forms the basis of the carat unit that we still use to measure precious metals, gemstones, and diamonds.

Time was measured by the positioning of the sun, moon, and stars. And volume would have been measured by filling pots and clay vessels for comparison.

The Romans then developed a more comprehensive system of measurement and spread it far and wide as the Holy Roman Empire stretched across much of the world. Many of the Roman units of measurement are still in use today - such as the foot, the mile, the pound, and the ounce - though they have been standardised now to an exactitude that the Romans did not have.

The symbol for the British Pound Sterling (£) actually comes from the Roman L, which denoted a Libra, the Latin word for a pound of silver.

Weights and measurements in the Middle Ages and the Renaissance

By the Middle Ages, the influence of the Roman Empire was still present in the measurement systems across much of Europe and North Africa. However, because there had not been a process of standardization, an English mile would have been a different length from a German, French, or Danish mile.

As well as there being differences within the old Roman units, there were also different measurements used altogether. For example, England used the 'perch,' roughly equivalent to 16.5 feet, which was not used anywhere else.

In England, there came the Composition of Yards and Perches sometime in the late 13th or early 14th century; the exact date is uncertain. This was a statute that sought to standardize the lengths of barleycorn, inches, feet, yards, perches, and acres. A few centuries later, Henry VIII standardized volumes of barrels to contain 36 gallons of beer or 32 of ale. A kilderkin was standardized as half of this and a firkin as half again.

However, despite varied attempts at standardizing certain measurements and units and the continued influence of the Roman system, there were multiple systems of measurement all over the world. As international trade, commerce, exploration, and colonization became an increasing factor in the development of economies, there was a growing need for a measurement system that could be universally converted.

Weights and measurements in the Industrial Revolution and Modern Times

The Industrial Revolution was a period of rapid economic and technological development in continental Europe, the UK, and the US, roughly between 1760 and 1840. It saw mass migrations of rural workers to cities, the onset of factory labor, and the advancement of what we now call capitalist economies based on the division of labor and the creation of credit for further investment in capital.

The period of the Industrial Revolution also saw many significant global events that took place within the context of industrialization, such as the expansion of the British Empire, the American War of Independence, and the French Revolution. As the global economy began to diversify, specific structures could no longer withhold such rapid change and either grew or crumbled under the pressure.

The French Revolution (1789 - 1799) was a critical event in the Industrial Revolution and represented a crucial moment in the historical timeline of weights and measurements. With the monarchy usurped and executed, the leaders of the new French Republic wanted to do away with all the old structures. This meant divorcing church from state, rewriting old laws, igniting campaigns for universal suffrage and slavery abolition, and rethinking antiquated systems of thought.

As part of the drive for change, the new leaders saw it fit to create a new calendar, new days of the week, and a new measurement system to replace the old one. While the new calendar and days of the week did not stick, the metric system developed in the wake of the French Revolution has become the international standard system of measurement.

The metric system was created to make a system of measurement that would be universal and not favor any country or person over another. It was decided that the system would be entirely based on the linear measure of a meter (hence the name 'metric'), which at that time was defined as exactly 1/10,000,000th of the distance from the North Pole to the Equator.

One meter is 100 centimeters. One liter is equal to 1,000 cubic centimeters. One liter of water weighs exactly one kilogram. One kilogram is equal to 1,000 grams. Etc. The whole point of the metric system is that it is self-contained; even liquid measures can be defined by the meter. All measurements are relative to one another, and all measurements are based on the exact length of the meter.

Due to the need for a universal measurement system and the ensuing years of European colonialism that followed the French Revolution, much of the world quickly adopted the metric system as the standard measurement system.

However, one of the key countries not to adopt the metric system was Britain. And in 1824, the Weights and Measures Act created the standardized imperial system of measurement (inches, feet, pounds, ounces, miles, etc.). This was then spread to the British colonies throughout the world.

Over time, the imperial system fell into decline as the metric system was regarded as more precise and easier to use. Today, only a few countries have not fully adopted the metric system, and most international organizations use it as the standard.

Weights and measurements in modern times

Today, there are only three countries that solely use imperial measurements and do not use any aspect of the metric system:

  • USA
  • Liberia
  • Myanmar

The main reason behind the reluctance of these countries to adopt the metric system is the time and money it would cost to make the shift.

A handful of other countries use a combination of the metric system and the old imperial system. For example, the UK has officially adopted the metric system, but road signs are still written in miles.

As we saw earlier, the metric system is based on the length of the meter. However, the precise length of the meter has changed over the years. Initially, a meter was based on the distance from the North Pole to the Equator, though that was soon converted into a prototype meter bar. Then it was redefined in the 1960s in terms of the number of wavelengths of a certain emission line of the element krypton. From 1983 until 2019, the meter was defined as the length of the path traveled by light in a vacuum in 1/299792458 of a second. Today, it is measured the same as it was up to 2019, but the definition of a second has been adjusted to a more precise measurement.

Given the number of times, the definition of a meter has been adjusted in the past, it will likely continue to change as more and more precise measurements become possible.

When did the Weights and Measures Act come into existence?

The Weights and Measures Act came into existence in 1985. The Act marked a significant step in the process of metrication in the UK.

The Act stated that units of length would be measured in meters and yards, and units of weight would be measured in kilograms and pounds. Pounds were to be defined in relation to kilograms, with one pound equal to 0.45359237 kilograms, and yards were to be defined in relation to meters, with one yard equal to 0.9144 meter.

Weights and measurements in the 21st Century

There continue to be changes made to the precise definitions of weights and measurements to this day. In 2019 there was a review of the base SI units (seconds, meters, kilograms, amperes, kelvins, moles, and candelas).

While we continue to draw closer to an exact system of measurement that is universally applicable, we have yet to create an entirely infallible system that leaves no room for variation; and we may never do so. This means that we will continue to reevaluate and define our measurement systems as our technology improves, and we can make observations with further precision.


Systems of measurement allow humans to see the world through the same eyes. The development of such systems is key to the flourishing of civilizations as they permit trade, commerce, and construction. Over thousands of years, we have created and lost many measurement systems, all in an effort to find a way of dividing and demarcating the world around us.

The metric system is now the international standard system of measurement, but given the impossibility of making exact measurements, it will likely continue to be revised to bring us ever closer to exactitude and precision.