What is pound?
A pound is a unit of mass in imperial and US customary systems equal to 16 ounces. It is widely used in the United States for body weight, grocery shopping, and general weight measurement.
Real-world uses
Pounds are the primary unit of weight in everyday American life—used for body weight, grocery items, luggage limits, and newborn birth weights. In the UK, pounds remain common for body weight despite official metrication.
History
The pound descends from the Roman "libra pondo" (a pound by weight), which is why its abbreviation is "lb." The avoirdupois pound was standardized internationally in 1959 as exactly 0.45359237 kilograms.
Common mistakes
Confusing pounds-mass (lb) with pounds-force (lbf), which are technically different quantities. Also, assuming the pound symbol "£" relates to weight—it actually denotes British currency, though both derive from "libra."
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?
Body weight, grocery items, and luggage limits are commonly expressed in kilograms in most countries and pounds in the US and UK, making this one of the most frequently needed mass conversions.
Worked examples
1 pound = 0.00044643 long ton (UK)
1 long ton (UK) = 1,016.0469088 kilogram
How to convert pound to long ton (UK)
To convert pound to long ton (UK), multiply the value by 0.00044643.
To convert long ton (UK) back to pound, multiply by 2,240.
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: pound to long ton (UK)
| pound | long ton (UK) |
|---|---|
| 0.1 | 0.00004464 |
| 0.5 | 0.00022321 |
| 1 | 0.00044643 |
| 2 | 0.00089286 |
| 5 | 0.00223214 |
| 10 | 0.00446429 |
| 25 | 0.01116071 |
| 50 | 0.02232143 |
| 100 | 0.04464286 |
| 250 | 0.11160714 |
| 500 | 0.22321429 |
| 1,000 | 0.44642857 |
Common values
| pound | long ton (UK) | |
|---|---|---|
| A paperclip | 2.20462262 pound | 0.00098421 long ton (UK) |
| A smartphone | 385.80895882 pound | 0.17223614 long ton (UK) |
| A bag of sugar | 2.20462262 pound | 0.00098421 long ton (UK) |
| Average adult human | 154.32358353 pound | 0.06889446 long ton (UK) |
| A small car | 2,645.54714622 pound | 1.18104783 long ton (UK) |