What is kilogram?
The kilogram is the SI base unit of mass. It is used globally as the standard for measuring weight and mass in science, industry, trade, and everyday life.
Real-world uses
The kilogram is the SI base unit of mass, used universally in science, commerce, and daily life outside the US. Grocery items, body weight in medical settings, and shipping weights are measured in kilograms across most of the world.
History
Originally defined in 1795 as the mass of one litre of water at 4°C. A platinum-iridium cylinder served as the standard from 1889 until 2019, when the kilogram was redefined in terms of the Planck constant, ending reliance on a physical artefact.
Common mistakes
Confusing mass (kg) with weight (newtons)—a kilogram measures mass, not force. Also, assuming 1 kg equals exactly 2 pounds; it is actually about 2.205 pounds.
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?
Converting between kilogram and long ton (UK) is common when working across metric and imperial systems, such as international trade, travel between countries with different measurement standards, or following instructions from a different region. 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 kilogram = 0.00098421 long ton (UK)
1 long ton (UK) = 1,016.0469088 kilogram
How to convert kilogram to long ton (UK)
To convert kilogram to long ton (UK), multiply the value by 0.00098421.
To convert long ton (UK) back to kilogram, multiply by 1,016.0469088.
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: kilogram to long ton (UK)
| kilogram | long ton (UK) |
|---|---|
| 0.1 | 0.00009842 |
| 0.5 | 0.0004921 |
| 1 | 0.00098421 |
| 2 | 0.00196841 |
| 5 | 0.00492103 |
| 10 | 0.00984207 |
| 25 | 0.02460516 |
| 50 | 0.04921033 |
| 100 | 0.09842065 |
| 250 | 0.24605163 |
| 500 | 0.49210326 |
| 1,000 | 0.98420653 |
Common values
| kilogram | long ton (UK) | |
|---|---|---|
| A paperclip | 1 kilogram | 0.00098421 long ton (UK) |
| A smartphone | 175 kilogram | 0.17223614 long ton (UK) |
| A bag of sugar | 1 kilogram | 0.00098421 long ton (UK) |
| Average adult human | 70 kilogram | 0.06889446 long ton (UK) |
| A small car | 1,200 kilogram | 1.18104783 long ton (UK) |