What is ounce?
An ounce is a unit of mass in imperial and US customary systems equal to approximately 28.35 grams. It is frequently used in cooking, food portioning, and the measurement of precious metals.
Real-world uses
Ounces are used in the US and UK for food packaging, postal weights, and cooking recipes. Precious metals are weighed in troy ounces (slightly heavier than avoirdupois ounces) on commodity exchanges worldwide.
History
The word "ounce" comes from the Latin "uncia," meaning one-twelfth (of a Roman pound). The avoirdupois ounce became standard in English trade by the 14th century, defined as 1/16 of an avoirdupois pound.
Common mistakes
Confusing avoirdupois ounces (28.35 g, used for general weight) with troy ounces (31.10 g, used for precious metals) or fluid ounces (a volume measure). These are three distinct units sharing the name "ounce."
What is long ton (UK)?
A long ton is a unit of mass historically used in the United Kingdom, equal to 2,240 pounds. It is used in shipping, naval architecture, and some industrial contexts in the UK.
Real-world uses
The long ton was historically used in British shipping, coal mining, and iron/steel trade. Naval vessel displacement is sometimes still quoted in long tons. It occasionally appears in older British engineering specifications and historical trade records.
History
The long ton of 2,240 pounds derives from the traditional English system of 20 hundredweight (each 112 lb). It was the standard British ton until metrication in the 1970s largely replaced it with the metric tonne in commerce.
Common mistakes
Confusing the long ton (2,240 lb / 1,016 kg) with the short ton (2,000 lb / 907 kg) or the metric tonne (2,205 lb / 1,000 kg). This 12% difference can cause major commercial discrepancies.
When is this conversion used?
Cooking recipes and food packaging often switch between grams and ounces, especially when adapting recipes from different culinary traditions.
Worked examples
1 ounce = 0.0000279 long ton (UK)
1 long ton (UK) = 1,016.0469088 kilogram
How to convert ounce to long ton (UK)
To convert ounce to long ton (UK), multiply the value by 0.0000279.
To convert long ton (UK) back to ounce, multiply by 35,840.
Measurement standards
The kilogram is defined by fixing the Planck constant to exactly 6.62607015 × 10⁻³⁴ joule-seconds, as established at the 26th General Conference on Weights and Measures in 2018. This ended the last SI definition based on a physical artefact.
Did you know?
The International Prototype of the Kilogram, a platinum-iridium cylinder stored near Paris since 1889, was found to have drifted by about 50 micrograms relative to its copies over a century — roughly the mass of a fingerprint.
Quick reference: ounce to long ton (UK)
| ounce | long ton (UK) |
|---|---|
| 0.1 | 0.00000279 |
| 0.5 | 0.00001395 |
| 1 | 0.0000279 |
| 2 | 0.0000558 |
| 5 | 0.00013951 |
| 10 | 0.00027902 |
| 25 | 0.00069754 |
| 50 | 0.00139509 |
| 100 | 0.00279018 |
| 250 | 0.00697545 |
| 500 | 0.01395089 |
| 1,000 | 0.02790179 |
Common values
| ounce | long ton (UK) | |
|---|---|---|
| A paperclip | 35.27396195 ounce | 0.00098421 long ton (UK) |
| A smartphone | 6,172.94334118 ounce | 0.17223614 long ton (UK) |
| A bag of sugar | 35.27396195 ounce | 0.00098421 long ton (UK) |
| Average adult human | 2,469.17733647 ounce | 0.06889446 long ton (UK) |
| A small car | 42,328.7543395 ounce | 1.18104783 long ton (UK) |