Ounces to Roman Ounces (oz to uncia)

1 ounce equals 1.034654129 Roman ounces (rounded).

1 ounce = 1.034654129 Roman ounces

How to convert ounces to Roman ounces

To convert ounces to Roman ounces, multiply the number of ounces by 1.034654129. The factor is rounded to 10 significant digits. To go the other way, multiply Roman ounces by 0.9665065574 (rounded).

Roman ounces = ounces × 1.034654129

Example: 10 ounces = 10.34654129 Roman ounces.

Approximate value. Standards for the Roman ounce (uncia) varied by place and period, so this converter uses the most commonly cited value. Treat results as estimates, not exact figures.

About these units

Ounce (oz)

US & ImperialCurrent unit

One sixteenth of a pound, exactly 28.349523125 g. Used for food, mail and consumer goods in the US and UK.

A twelfth part is what ounce originally meant. It comes from the Roman uncia, one twelfth of the Roman pound, a word that also gave English the inch. The abbreviation oz does not come from English at all but from the Italian onza or oncia. Over the centuries many regions and trades used different ounces: the English Tower ounce of 29.16 g was abolished by Henry VIII in 1527, and the Dutch ons was redefined as exactly 100 g in 1820.

The avoirdupois ounce used for everyday goods is one sixteenth of a pound, exactly 28.349523125 g or 437.5 grains, the standard in the US and under the UK imperial system. It is not the same as the troy ounce for precious metals, and neither is the fluid ounce, which measures volume. Ounces still describe portions such as steaks and burgers, and they show up in unexpected places: fabric is graded by weight per area, so a 16 oz denim is a heavy cloth, and the copper on a circuit board is specified in ounces, where 1 oz is roughly 34.7 micrometres thick.

1 ounce = 0.02834952313 kilograms (approximately).

Sources: Wikipedia: Ounce; NIST Guide to the SI, Appendix B.8 (mass conversions)

Roman Ounce (uncia) (uncia)

Ancient RomanHistorical unit (no longer in standard use)Approximate value

One twelfth of a Roman pound, about 27.4 g. The origin of the word 'ounce'.

Literally meaning a twelfth, uncia was the Roman name for one part in twelve, applied to weight, length and more. As a weight it was a twelfth of a libra. The same word, used for a twelfth of a foot, produced the English inch, so inch and ounce are cousins that split from a single Latin source.

With the libra put at 328.9 g, the uncia comes to about 27.4 g, which is the figure used here. That is a little under the modern avoirdupois ounce of 28.35 g and well below the troy ounce of about 31.1 g. Because the libra itself is estimated anywhere from 322 to 329 g, an uncia could be anywhere from about 26.8 to 27.4 g.

The unit outlived Rome. It continued as the Byzantine ounce, known in Greek as oungia, and in time spread into medieval trade systems across Europe. Many regional ounces developed, such as the Tower ounce and the Dutch ons, which was fixed at 100 g in 1820.

1 Roman ounce (uncia) = 0.0274 kilograms (approximately).

Sources: Wikipedia: Uncia (unit); Wikipedia: Ounce; Wikipedia: Roman pound

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