The roots of the British Imperial System are nearly 2000 years old. Roman, Celtic, and Anglo-Saxon traders used various units of measurement, some of which are still in use today. For example, the ounce is a roman measurement. The ounce is derived from the Roman word Unica, which means 'twelfth part'. An ounce was one-twelfth of a Roman foot. A Roman foot was also a Roman pound. Weight and length (feet and pounds) were made using a copper bar split into 12 pieces. These pieces were called Unciae and designated units of weight and length. This is how the modern measurements of inches and ounces came to be. One of the 12 parts would measure an inch and weigh an ounce.

During the reign of George IV in 1824, a standard system of weights and measures was established. The Weights and Measures Act was established in 1824 and later improved in 1878. This was to give scientific standardisation to weights and measurements to aid trading in Britain. Traders would no longer have to estimate stock or deal with various different methods and measurements to weigh stock. Instead, there was one official way to measure and weigh products which helped streamline trading.

The expansion of the British Empire also took the Imperial system across the globe, including the USA. However, after the French revolution, most of the world adopted the new, more accurate metric system. The US is now one of the last countries to still use the Imperial System, which includes ounces. Confusingly, the UK often uses both systems interchangeably, although the official system is the Metric System.

Trade in the UK and the US can be confusing as you often need to switch between Imperial and Metric. Luckily there are unit converters online to help ease the process. This article will focus on the ounce, in particular, and will explain the difference between fluid ounces and solid ounces.

A dry ounce, more commonly known as an ounce, is a weight measurement used to measure how much something weighs. However, to further confuse the issue, two different types of ounces are in use. These are the avoirdupois ounce and the troy ounce. The avoirdupois ounce is an Anglo-Norman French word meaning goods of weight. There are 16 ounces to one pound. However, the actual weight of both these ounces differs. The Avoirdupois ounce weighs 28.35 grams, whilst the troy ounce is 31.10 grams.

The international avoirdupois ounce is mainly used to measure the weight of stock, like food items. The international troy ounce, on the other hand, is used to weigh precious metals, like gold.

The difference between fluid ounces and dry ounces is that fluid ounces measure volume whilst dry ounces measure weight. Also, there are two different systems to measure fluid ounces. For example, a US customary fluid ounce is 29.5735297 ml. However, the imperial fluid ounce is only 28ml. The US fluid ounce differs because they gained independence from the UK before the 1824 act was established.

The US fluid ounce is based on the US gallon. The US gallon is based on the wine gallon. There are 128 fluid ounces per gallon using the customary system. Before the 1824 act was established, the UK also used the wine gallon.

However, the British imperial gallon contained 160 fluid ounces. This would be further broken down into imperial units. For example, an imperial quart is a quarter of a gallon. Each quart contained two pints, each pint consisted of four gills, and each gill has five fluid ounces.

The international confusion between the different measurement systems can be seen in many aspects of life. For example, in the fitness industry. Europeans use kilograms whilst Americans use pounds when lifting weights. When a fitness influencer, for example, talks about how much weight they lift or weight-range recommendations for lifting, it often becomes confusing. Europeans then have to convert that from kilograms to pounds, or pounds to kilograms for Americans.

Often this means you cannot follow their workout plan or recommendations accurately. For example, if they tell you to lift 60 pounds, the weight converts to 27.2155 kilograms. There are no 27.2155 weights at the gym. Weights are categorized into whole numbers, usually in multiples of five or 10 kilograms.

Grams are a more accurate, more coherent unit of measurement than ounces. This is because they use a decimal system which makes calculations easier. Grams and their multiples are far better for calculating small measurements in particular. Also, unlike ounces that use the avoirdupois and troy measurements, there is only one type of gram.

The confusion amongst differing measurement systems can often have disastrous consequences. This was evidenced by a failed Mars Climate Orbiter launch in 1998. As it turned out, the spacecraft and base computer on the ground were using different measuring systems to calculate the trajectory. The spacecraft was using Newton seconds (metric), whilst the processing software on the ground used pound seconds (imperial). This meant that every time the ground team changed the trajectory of the craft, the measurement was incorrect. When the orbiter reached mars, contact was lost.

The safety issues presented in using different measurements are also an extreme concern in the medical industry. Pinpoint accuracy is needed to administer and prescribe medication. Often the weight of a patient is used to calculate their dosage of drugs. Any miscalculation when converting imperial to metric or vice versa could cause serious problems.

In terms of liquid, millilitres and their multiples are the gold standard for measuring. This is because they are extremely precise in small numbers. However, even so, medicine is often prescribed in doses of teaspoons or tablespoons. This can often save time but presents a danger of over or under-dosing a medicine.

The Imperial System emerged in Britain as early as 2000 years ago. In 1824 an act was introduced to standardize all measurements under one system.

The majority of the world switched to the more efficient metric system when it was established after the French revolution. However, the US did not make the switch, and the UK use a combination of both, but mainly metric. Unsurprisingly this can make measurements and conversions confusing.

Dry ounces measure weight, and there are two different types of dry ounces - avoirdupois and troy.

There are also two different types of fluid ounces. The imperial ounce is 28ml, while the US customary fluid ounce is 29.5735297 ml.

Both grams and millilitres are much more accurate than dry and liquid ounces. They are especially more beneficial when breaking down small quantities for cooking or administering medicine, where accuracy is key.