Alanna Madden
May 28, 2021
Grammar Tips

A tonne is a metric ton (1,000 kg) or the equivalent of one megagram (Mg). A ton is either a short ton (907.2 kg) or a long ton (1,016.05 kg).

What is the difference between ton and tonne?

The words ton and tonne are units of measurement for mass (and a lot of it). But while these terms have the same pronunciation and similar spellings, we cannot use them interchangeably.

The tonne (t) is a metric unit of mass equal to 1,000 kg or 2,205 pounds.
A ton is an imperial measurement that can mean “short ton” (907.2 kg) or “long ton” (1,016.05 kg).

Both terms reference an incredible amount of mass, and there’s a good reason why their meanings are so similar (especially when we use “ton” to describe “a lot” of something).

Origins of ton and tonne

The word ton is a Middle English variant of tun, a term that historically referenced the heaviest cask used for international wine trade (about 954 liters or 252 gallons). Depending on the consistency of wine back then, this means each of these massive wine barrels would have topped out around 2,050 pounds, which is pretty similar to the modern understanding of “ton” and “tonne.”

According to the Encyclopedia Britannica, the “tun” acquired its name from French tonnerre (meaning “thunder”) after the loud rumbling sounds made while rolling barrels in transport. In fact, the tun was so heavy that English speakers used the term for anything large up until the 17th century.

Now, barrels were common objects back in the colonial days, so there were several standardized terms to differentiate barrel measurements (as writer Jeremy M. Bell puts it: “barrels were the colonial Tupperware”). After the 252 gallon tun, there was the pipe barrel (126 gallons), the hogshead (64 gallons), and then the standard barrel (32 gallons), and similar measuring systems would go on to establish the “ton” and “tonne” as we know them today.

What is a tonne?

The tonne (t) is a metric unit of mass equal to 1,000 kilograms (kg), 2,205 avoirdupois pounds (lbs), but most English-speaking countries associate the tonne with a “metric ton.”

The tonne and its symbol “t” were adopted by the International Committee for Weights and Measures (CIPM) in 1879, four years after the Metre Convention. Since then, the tonne (or “metric ton”) has been recognized by the International System of Units (SI) as a “non-SI” unit of mass, providing the tonne with a metric equivalent of one “megagram” (abbreviated as Mg).

All multiples of tonne with metric prefixes include:

1 tonne (10⁰) ≅ tonne (t) ≅ 10⁶ megagram (Mg)
1 thousand tonnes (10³) ≅ kilotonne (kt) ≅ 10⁹ gigagram (Gg)
1 million tonnes (10⁶) ≅ megatonne (Mt) ≅ 10¹² teragram (Tg)
1 billion tonnes (10⁹) ≅ gigatonne (Gt) ≅ 10¹⁵ petagram (Pg)
1 trillion tonnes (10¹²) ≅ teratonne (Tt) ≅ 10¹⁸ exagram (Eg)
1 quadrillion tonnes (10¹⁵) ≅ petatonne (Pt) ≅ 10²¹ zettagram (Zg)
1 quintillion tonnes (10¹⁸) ≅ exatonne (Et) ≅ 10²⁴ yottagram (Yg)

How to use tonne in a sentence?

“When running at full capacity, TNT Plastics converts a tonne of plastic raw materials into chairs, buckets, cups, dishes and utensils over the course of three shifts a day.” — Al Jazeera
“It forces power plants, factories and airlines running European flights to buy a permit for each tonne of CO2 they emit, effectively putting a price on pollution.” — Reuters
“Littmann said transporting the trees had released up to 55 tonnes of carbon dioxide.” — The New York Times
“Scientists say the risk of debris from the 22-metric-ton rocket stage hitting people or causing property damage is extremely low.” — The Washington Post

What is a ton?

Throughout many English-speaking countries, “ton” is an informal noun that describes a large number or great amount of something. But in comparison to “tonne,” the word “ton” is an Imperial measurement with distinct meanings for American and British English:

In the United States, a ton, short ton (ST), or US ton is the equivalent of 907.2 kg or 2,000 lbs.
The long ton (LT) or weight ton (W/T) is synonymous with the British imperial ton, a unit of measurement equal to 1,016.05 kg or 2,240 lbs.

Why is there an American ton and a British ton?

The US ton and British ton exists because, at one time, both countries utilized the same measuring system units. However, once Britain passed the Weights and Measures Act 1824, several measurements of these changed, and America felt no pressure to oblige their former sovereignty. In fact, the US introduced its own customary measuring system, resulting in notable measurement differences like the “short ton” and the “long ton.”

Traditionally, the “ton” was the equivalent of 20 hundredweight (cwt), with each unit weighing 100 pounds or 45.36 kg (this is why British English uses the word “ton” to reference 100 mph, £100, etc.). After 1824, this number changed to 20 hundredweight of 8 stones (14 lbs each), making the new hundredweight 112 lbs or 50.80 kg.

The result:

1 short ton (US) = 20 short hundredweight = 100 lbs*20 = 2,000 lbs
1 long ton or “imperial ton” = 20 long hundredweight = (8*14)*20 = 2,240 lbs

How to use ton in a sentence

“Benchmark spot iron ore prices topped $200 a ton for the first time ever, while futures in Singapore and China climbed.” — Bloomberg
“There are a ton of different combinations of materials out there and it’s intimidating if you don’t know what’s actually considered recyclable.” — Seventeen Magazine
“Tugs operated by Seattle’s Harley Marine Services towed the Vigilant from Portland, where it has been replaced by the 80,000-long ton capacity Vigorous, the largest floating dry dock in the country.” — Puget Sound Business Journal
“American hot-rolled steel coil recently sold for $900 per short ton—the highest price in a decade.” — Wall Street Journal

What does ton mean for specific trades?

Most dictionaries provide definitions of ton that include figures outside of the metric ton or US ton. That’s because the “ton” has adopted several meanings for agricultural trade, maritime shipping, and more. Let’s have a look.

Displacement ton

The “imperial ton” or “long ton” also goes by the name “displacement ton” when it measures a ship’s water displacement equal to 35 cubic feet or 0.99 cubic meters. However, a “displacement ton” is not the same concept as “tonnage,” a term that references the weight capacity of a ship.

Register ton

The register ton (also known as a gross ton or gross register ton) is a unit of gross internal capacity equal to 100 cubic feet or 2.83 cubic meters. Under the same category, Lexico alternatively defines a gross ton as “a unit of refrigerating power able to freeze 2,000 lb of water at 0°C in 24 hours.”

Freight ton

The freight ton or “measurement ton” is a unit of weight or volume for sea cargo totaling one metric ton (1,000 kg) or 40 cubic feet.

English water ton

The English water ton is a unit of volume for petroleum products equal to 224 British Imperial Gallons (imp gal) or 269.013 US liquid gallons (gal).

Timber ton

Similar to “register ton,” a timber ton is a unit of gross internal capacity equal to 40 cubic feet or 1.12 cubic meters.

The wheat ton and other grain units

The word ton or tonne frequently occurs within agricultural terms like “wheat ton” or “barley ton” to convert metric ton units of dry grain to an imperial or US bushel (bu).

Conversion factors from the US Grains Council include:

Barley ton (48 lb/bu): 45.9296 US bu = 2,204.6 lbs
Corn ton/Sorghum ton (56 lb/bu): 39.368 US bu = 2,2204.61 lbs
Wheat ton/Soybean ton (60 lb/bu): 36.7436 US bu = 2,2204.62 lbs

FAQ: Related to ton vs. tonne

Which is heavier: a ton or a tonne?

The tonne or metric ton weighs 2,205 pounds, so it’s 205 pounds heavier than the US ton. At 2,240 pounds, the “British ton” weighs more than the tonne by 35 pounds.

What’s the difference between US customary measurements vs. the metric system?

US customary units are typically measured and reported in the following ways:

Length: inch (in), foot (ft), yard (yd), mile (mi).
Weight: ounce (oz), pound (lb), short tons (ST).
Volume: fluid ounce (fl oz), cup, pint (pt), quart (qt), gallon (gal).

The International System of Units (SI) or “modern metric system” reports measurements of length, weight, and volume using meters (m), grams (g), and liters (L).

Length: centimeters (cm), meters (m), kilometers (km).
Weight: grams (g), kilograms (kg).
Volume: milliliters (mL), liters (L).

Additionally, the SI indicates the size of metric measurements using decimal multiples and submultiples from 10²⁴ to 10^-24. Prefixes are available to powers of ten, such as deca-, hecto-, kilo-, mega-, giga, and tera-.

Although the US has not fully embraced the metric system, Americans who work in government, STEM, and health care fields use the following SI units on a regular basis:

SI Base Units:

Meter for length (m)
Kilogram for mass (kg)
Second for time (s)
Ampere for electric current (A)
Kelvin for thermodynamic temperature (K)
Candela for luminous intensity (cd)
Mole for the amount of substance (mol)

Common SI derived units:

Radian (rad): plane angle
Hertz (Hz): frequency
Newton (N): force, weight
Pascal (Pa): pressure, stress
Joule (J): energy, work, heat
Watt (W): power/radian flux
Coulomb (C): electric charge
Volt (V): voltage, electromotive force (emf)
Ohm (Ω): resistance, impedance, reactance
Siemens (S): electrical conductance
Henry (H): inductance
Celsius (°C): temperate relative to 273.15 K
Lumen (lm): luminous flux
Becquerel (Bq): radioactivity

Common derived quantities:

Area (A): square meter (m²)
Volume (V): cubic meter (m³)
Speed/Velocity (v): meters per second (m/s)
Acceleration (a): meters per second squared (m/s²)
Density (p): kilogram per cubic meter (kg/m³)

Non-SI Units compatible with SI units

Minute (min), hour (h), and day (d) for time
Astronomical unit (au) for length
Degree (°), minute (‘), and second (“) for plane and phase angle
Hectare (ha) for area
Liter (L) for volume
Tonne (t) and dalton (Da) for mass
Electronvolt (eV) for energy
Neper (Np), bel (B), and decibel (dB) for logarithmic ratio quantities

Test Yourself!

Test how well you understand the difference between ton and tonne with the following multiple-choice questions.

True or false?: the metric system is not utilized in North America.
a. True
b. False
The tonne is a ________.
a. Unit of volume
b. Unit of force
c. Unit of mass
d. Unit of energy
In colonial times, a half-tun barrel was called a ________.
a. Hogshead
b. Drum
c. Pipe barrel
d. Standard barrel
In the United States, a ton of bricks weighs ________ lbs.
a. 2,205
b. 2,000
c. 2,210
d. 2,240
If someone says they have a “ton of food,” it means they have ________.
a. 1,000 kg of food
b. A lot of food
c. 100 packages of food
d. All of the above
Which of the following tons references a unit of capacity?
a. Timber ton
b. Register ton
c. Imperial ton
d. A and B
You are asked to break apart a short ton of ice into ice cubes with a volume of 0.03 kg. How many complete ice cubes can you make?
a. 35,840
b. 32,000
c. 35,273
d. 32,001
Which of the following is an SI unit of energy, work, and heat?
a. Newton (N)
b. Radian (rad)
c. Joule (J)
d. Watt (W)

Answers

Sources

Bell, J. M. “Put it in a hogshead.” The Economy of Goods, UCF History Department, 2019.
“Converting grain units.” U.S. Grains Council, grains.org, 2021.
“Hundredweight.” Cambridge Dictionary, Cambridge University Press, 2021.
“The International System of Units.” 9th ed, vol. 1.08, pp. 127–145, The International Bureau of Weights and Measures (BIPM), 2019.
“Metric ton.” Lexico, Oxford University Press, 2021.
The Editors of Encyclopaedia Britannica. “Ton.” Encyclopedia Britannica, britannica.com, 6 Apr 2011.
“Ton.” The American Heritage Dictionary of the English Language, 5th ed., Houghton Mifflin Harcourt Publishing Company, 2021.
“Ton.” Lexico, Oxford University Press, 2021.
“Tonne.” Lexico, Oxford University Press, 2021.

Alanna Madden

Alanna Madden is a freelance writer and editor from Portland, Oregon. Alanna specializes in data and news reporting and enjoys writing about art, culture, and STEM-related topics. I can be found on Linkedin.

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