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 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.
When is this conversion used?
Converting between ounce and tonne 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. Cooking recipes and food packaging often switch between grams and ounces, especially when adapting recipes from different culinary traditions.
Worked examples
1 ounce = 0.00002835 tonne
1 tonne = 1,000 kilogram
How to convert ounce to tonne
To convert ounce to tonne, multiply the value by 0.00002835.
To convert tonne back to ounce, multiply by 35,273.96194958.
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 tonne
| ounce | tonne |
|---|---|
| 0.1 | 0.00000283 |
| 0.5 | 0.00001417 |
| 1 | 0.00002835 |
| 2 | 0.0000567 |
| 5 | 0.00014175 |
| 10 | 0.0002835 |
| 25 | 0.00070874 |
| 50 | 0.00141748 |
| 100 | 0.00283495 |
| 250 | 0.00708738 |
| 500 | 0.01417476 |
| 1,000 | 0.02834952 |
Common values
| ounce | tonne | |
|---|---|---|
| A paperclip | 35.27396195 ounce | 0.001 tonne |
| A smartphone | 6,172.94334118 ounce | 0.175 tonne |
| A bag of sugar | 35.27396195 ounce | 0.001 tonne |
| Average adult human | 2,469.17733647 ounce | 0.07 tonne |
| A small car | 42,328.7543395 ounce | 1.2 tonne |