The imperial system is a system of measurement that brought together a whole host of units that could be precisely defined in relation to one another. Also known as the "British Imperial System," it was formally developed in Britain, though it has roots in other measurement systems dating back thousands of years.

Although in most countries, the imperial system has been replaced by the metric system, many imperial measurements are still in use today. The UK still uses miles, for example. And the US Customary System is heavily based on the imperial system and shares many of the same unit values.

So when was the imperial system developed? Why was it replaced by so many countries? And did anyone actually invent the imperial system, or was it the accumulation of millennia of antecedents?

We are going to find out the answer to all these questions and more as we explore who invented the imperial system.

The imperial system was formalised and codified by the British in the 19th century. However, it evolved from thousands of years of local, customary units that were used by the Romans, Celts, Anglo-Saxons, and other people throughout Europe, North Africa, and the near East.

The imperial system then spread across the world as it was used as the standard measurement system for colonies in the British Empire. However, since the mid-20th century, the imperial system has been gradually replaced by the metric system, and there are now only a handful of countries in the world that use the imperial system or the US Customary System.

So let's now jump in and find out where the imperial system started and how it was developed.

Where did the imperial system come from?

Many of the measurements used in the imperial system date back thousands of years and used the same traditional names used today - such as foot, pound, yard, and gallon - though other names were also used depending on the time, place, and what was being measured.

In the 10th century, King Edgar the Peaceable kept a royal bushel (equivalent to 8 gallons or 36.4 litres). As Winchester was the King's place of residence at this time, the name given to early standardised measurement systems in Britain was the "Winchester measure."

The Winchester measure then expanded over the next few centuries to incorporate yards, feet, inches, and units of capacity.

King Henry VII distributed royal standards that affirmed the exact measurements throughout the realm in the late 15th century. This was the first attempt at creating a national standard for unit measurements.

Queen Elizabeth I then repeated this process a century later with new units, such as the rod.

When was the imperial system created?

As we have seen, the imperial system evolved over a long period of time before it became formalised. However, the Weights and Measures Act of 1824 and its review in 1878 formally established the imperial system under the name of the "British Imperial System."

The British Imperial System laid out precise measurements of existing units and added in other basic standard units.

It was then spread and used across the colonies within the British Empire, including India, Canada, New Zealand, Hong Kong, and Australia.

Which countries use the imperial system?

Initially, the imperial system was used across the British Empire, which covered about a quarter of the world's population.

Today, only one country in the world officially uses the imperial system, which is Myanmar. The USA and Liberia use the US Customary System, which is very similar to the imperial system.

However, many other countries still use elements of the imperial system though it is not the official measurement system.

What is the metric system?

The metric system is another system of measurement that was developed in the late 18th century after the French Revolution.

After the Revolution, the French National Assembly proposed reforms to a number of the outdated systems that were still in use, including the measurement system.

The metric system is based on the metre, which is defined as 1 / 299,792,458 of the distance that light travels in a second. One metre is then figured as 100 centimetres, and 100 metres is one kilometre.

The metric system is simpler, more precise, and easier to convert than the imperial system.

It was used by the French from the late 18th century and spread throughout the French colonies during the colonial period.

From the mid-20th century onwards, countries around the world began to adopt the metric system as the measurement standard in place of the imperial system. It is now the most commonly used measurement system in the world.

When was the imperial system dropped in the UK?

The UK officially uses the metric system and has done so since joining the EU in the 1970s. However, there are still many elements of the imperial system used in the UK, especially when it comes to distance measurements and roads, and most people are familiar with aspects of both the metric and imperial systems.

The process of replacing imperial units with the metric system in the UK has made steady and continual progress since the mid-20th century. However, officially adopting the metric system was even discussed in parliament as early as 1818.

But it wasn't until 1965 that a formal government policy to support metrication was agreed upon. And then, when the UK joined the European Economic Community (now known as the EU) in 1973, it was obligatory for member states to incorporate all EU directives, including the standardised metric measurement system.

By 1980, almost all pre-packaged goods used metric measurements on the packaging. And by 2000, it was made mandatory that all goods used metric measurements for sale purposes.

What is the US Customary System?

The US Customary System (USCS) is a measurement system that is used in the US and was standardised in 1832.

The USCS was directly developed from the units used in Britain prior to the official establishment of the British Imperial System.

Most of the USCS units are the same as the British imperial units, but there are a few key differences.

The imperial system today

Today, the imperial system is used less and less frequently as the metric system has been adopted by most countries in the world and is now regarded as the international standard.

Many people worldwide still use miles over kilometres and feet instead of metres, even if the country they live in has officially switched to the metric system.

In 2022, the former UK prime minister Boris Johnson suggested bringing back imperial measurements as a celebration of the Queen's Platinum Jubilee. The plans were met with much derision and were widely mocked for being outdated and pointless.

Unit conversions

Let's now look at some key unit conversions between the imperial and metric measurement systems.

Length conversions

Metric to imperial:

1 millimetre [mm]0.03937 in
1 centimetre [cm](10 mm)0.3937 in
1 metre [m](100 cm)1.0936 yd
1 kilometre [km](1000 m)0.6214 mile

Imperial to metric:

1 inch [in]2.54 cm
1 foot [ft](12 in)0.3048 m
1 yard [yd](3 ft)0.9144 m
1 mile(1760 yd)1.6093 km

Area conversions

Metric to imperial:

1 square centimetre [cm²]0.1550 in²
1 square metre [m²](10,000 cm²)1.1960 yd²
1 hectare [ha](10,000 m²)2.4711 acres
1 square kilometre [km²](100 ha)0.3861 mile²

Imperial to metric:

1 square inch [in²]6.4516 cm²
1 square foot [ft²](144 in²)0.0929 m²
1 square yard [yd²](9 ft²)0.8361 m²
1 acre(4840 yd²)4046.9 m²
1 sq mile [mile²](640 acres)2.59 km²

Volume conversions

Metric to imperial:

1 cubic centimetre [cm³]0.0610 in3
1 cubic decimeter [dm³](1,000 cm³)0.0353 ft3
1 cubic metre [m³](1,000 dm³)1.3080 yd3
1 litre(1 dm³)1.7598 pt

Imperial to metric:

1 cubic inch [in³]16.387 cm³
1 cubic foot [ft³]0.02832 m³
1 pint668 ml
1 gallon4.54 litres

Mass conversions

Metric to imperial:

1 gram [g]0.0353 ounce
1 kilogram [kg](1,000 g)2.2046 pounds
1 tonne [t](1,000 kg)1.1023 short ton

Imperial to metric:

1 ounce [oz]28.35 g
1 pound [lb](16 oz)0.4536 kg
1 stone(14 lb)6.3503 kg
1 hundredweight [cwt](112 lb)50.802 kg

The British Imperial System evolved over many years and was formalised by the Brits in the early 19th century. However, many of the units of measurement used in the imperial system had been around in one form or another for millennia before that. The rapid spread of colonialism and the power of the British Empire meant that the British system became the international system.

However, despite the attempts of some politicians, the metric system is now preferred by almost all countries, save a handful. But there are still imperial measurements to be found, especially in Britain, where pints, miles, and stone are still frequently cited.