What is tonne?
A tonne, also known as a metric ton, is a unit of mass equal to 1,000 kilograms. It is used in industrial shipping, cargo measurement, and large-scale material production and trade.
Real-world uses
Tonnes (metric tons) are used globally for cargo shipping weights, industrial raw materials, agricultural harvest yields, and carbon emissions reporting. A standard shipping container might carry up to about 28 tonnes of cargo.
History
The tonne derives from the Old French "tonne" meaning a large cask. It was formalized in the metric system as exactly 1,000 kilograms. Though not an official SI unit, it is accepted for use with SI and is the global standard in trade.
Common mistakes
Confusing the metric tonne (1,000 kg) with the US short ton (907.18 kg) or the Imperial long ton (1,016.05 kg). Using "ton" ambiguously without specifying which system creates significant commercial errors.
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 tonne 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.
Worked examples
1 tonne = 0.98420653 long ton (UK)
1 long ton (UK) = 1,016.0469088 kilogram
How to convert tonne to long ton (UK)
To convert tonne to long ton (UK), multiply the value by 0.98420653.
To convert long ton (UK) back to tonne, multiply by 1.01604691.
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: tonne to long ton (UK)
| tonne | long ton (UK) |
|---|---|
| 0.1 | 0.09842065 |
| 0.5 | 0.49210326 |
| 1 | 0.98420653 |
| 2 | 1.96841306 |
| 5 | 4.92103264 |
| 10 | 9.84206528 |
| 25 | 24.60516319 |
| 50 | 49.21032638 |
| 100 | 98.42065276 |
| 250 | 246.0516319 |
| 500 | 492.10326381 |
| 1,000 | 984.20652761 |
Common values
| tonne | long ton (UK) | |
|---|---|---|
| A paperclip | 0.001 tonne | 0.00098421 long ton (UK) |
| A smartphone | 0.175 tonne | 0.17223614 long ton (UK) |
| A bag of sugar | 0.001 tonne | 0.00098421 long ton (UK) |
| Average adult human | 0.07 tonne | 0.06889446 long ton (UK) |
| A small car | 1.2 tonne | 1.18104783 long ton (UK) |