Stones (st) to Long Tons (long-ton) conversion

What is the stone?

What is Stones?

Stones (abbreviated as "st") are a unit of mass primarily used in the United Kingdom and Ireland for measuring human body weight. One stone is equivalent to 14 pounds (lbs) or approximately 6.35 kilograms (kg). While officially deprecated for most purposes, it remains common in everyday conversation for expressing weight.

Historical Context and Formation

• Origin: The term "stone" originates from the practice of using stones as weights for measurement, a practice dating back to ancient times. The specific weight of a "stone" varied considerably across different regions and commodities for centuries.
• Standardization: The standardization of the stone to 14 pounds was formalized in the UK Weights and Measures Act of 1835. This act helped establish uniformity in trade and measurement.
• Why 14 pounds? The origin of 14 lbs is debated, some suggest it was a convenient amount for a man to carry while others trace it back to Roman times.

Mathematical Relationship

The relationship between stones, pounds, and kilograms can be expressed as follows:

• 1 stone (st) = 14 pounds (lbs)
• 1 pound (lb) ≈ 0.0714286 stones (st)
• 1 stone (st) ≈ 6.35029 kilograms (kg)
• 1 kilogram (kg) ≈ 0.157473 stones (st)

Conversion formulas:

• To convert pounds to stones:

  $$\text{Stones} = \frac{\text{Pounds}}{14}$$

• To convert kilograms to stones:

  $$\text{Stones} = \frac{\text{Kilograms}}{6.35029}$$

Usage and Examples

The primary application of stones is for expressing human body weight in the UK and Ireland. Here are some examples:

• "He weighs 12 stone 6" (meaning 12 stones and 6 pounds).
• A person might say, "I've lost half a stone" (meaning they've lost 7 pounds).

While not commonly used for other quantities, theoretically, one could express the weight of other items in stones. For example:

• A bag of potatoes weighing 28 pounds could be described as weighing 2 stones.
• A small dog weighing 35 pounds could be said to weigh 2.5 stones.

It is important to note that stones are generally not used for measuring anything other than human body weight in everyday conversation.

Interesting Facts

• Decimal Stones: While less common, there is a decimal stone, where the pound is divided decimally to give a fraction of a stone.
• Other Commodities: Historically, different regions used "stones" to measure varying weights of other commodities, like wool, but the 14-pound stone is now the standard.

Associated Figures

There isn't a specific law or person fundamentally linked to the stone besides its formalization in the Weights and Measures Act. However, due to its use in reporting body weight, health professionals in the UK and Ireland are familiar with this unit.

What is the Long Ton?

The long ton is a unit of mass in the British imperial system, historically used for weighing bulk commodities such as coal, ore, and shipping cargo. It is equal to 2,240 pounds and remains familiar in the United Kingdom and in maritime contexts.

Definition

The long ton is defined as exactly 2,240 pounds avoirdupois. Since one pound equals 0.45359237 kg exactly, its SI value is:

$$1\ \text{long-ton} = 1016.05\ \text{kg}$$

Equivalently, the long ton equals 20 hundredweight (cwt) of 112 lb each, distinguishing it from the 2,000 lb US short ton and the 1,000 kg metric tonne.

Origin and History

The long ton descends from the medieval English "tun," a large cask used to ship wine, whose full weight was standardized in trade. The avoirdupois system fixed the hundredweight at 112 pounds (eight stone of 14 lb), and twenty of these made the ton, giving 2,240 lb. This "long" hundredweight and ton became the standard for British commerce and were carried throughout the Commonwealth and colonial trade.

Law and Notable Facts

The long ton is the British/imperial ton, contrasted with the 2,000 lb US short ton and the 1,000 kg metric tonne (megagram). It is legally recognized in the United Kingdom, though the metric tonne has largely replaced it for official trade. Notably, the long ton (1016 kg) sits remarkably close to the metric tonne (1000 kg), differing by only about 1.6%, which is why "ton" and "tonne" are often used loosely as near-equivalents in shipping.

Real-World Examples and Conversions

• A long ton equals 1016.05 kg, about 16 kg heavier than a metric tonne.
• Ship displacement and cargo were traditionally quoted in long tons; a 10,000 long ton vessel carries roughly 10,160 metric tonnes.
• One long ton (2,240 lb) is 240 lb heavier than one US short ton (2,000 lb), a 12% difference.
• A long ton of coal (1016 kg) is a typical unit still cited in older British mining and heating records.