Roman measures

Roman measurement units were based on Greek and Egyptian standards. They were generally accurate and often used in everyday life. The Romans weighed everything from gold to vegetables using two types of scales: a simple bronze pan scale or a strong horizontal scale on a hook with a sliding weight, intended for weighing, for example, bags of flour.

Measurements of length

The basic unit of Roman length was the foot (pes). The foot was divided into smaller units: dodrans (3/4), bes (2/3), triens (1/3), quadrans (1/4), sextans (1/6), uncia (1/12), semiuncia (1 /24) and sicilius (1/24).
Distances were measured by separate measures: stride (gradus), double stride (passus), pole (guineafowl), length of furrow ploughed by oxen without stopping for rest (actus), a thousand paces (miliarium or milia passuum) and the cubit taken from the Egyptians (cubitus).

Area measures

The most common measure of the area was iugerum, which originally meant the area where a pair of oxen (hence the name from jugum, meaning “yoke”) could plough in a day. It was a field of 35.5 m by 71 m, amounting to 2520.6 m square.

When there was a need to use larger units, heredium, centuria and saltus were used. In Roman Egypt, arura was in common use.

Capacity measures

Measures of capacity are derived from vessels in which both liquid and loose products have been stored. For this purpose, separate series of measures were established for them. For liquids, the Romans took their measures of capacity from the Athenians. The system was established in the 3rd century BCE and did not undergo any major changes in later times. The basic unit for liquids was the sextarius. The same measures from the sextarius downwards were used to measure powdery substances. For larger quantities of these products, a modius of approximately 8 litres and a semimodius of 4 litres were used.

Measurements of mass

The basic unit of weight was libra, also called pondus. Libra from the 3rd century BCE had a fixed weight, not subject to major fluctuations thereafter.

Libra was divided into 12 ounces (1 ounce was equal to 27.288 g). Units such as the drachma and obolus came into use in imperial times. Siliqua and lupinus did not appear until the time of Constantine and were used to weigh gold. The smallest unit of Roman measurement was siliqua – the weight of a grain of a plant called “carob” (Certonia siliqua).

There were also units higher than libra:

Read more

Monte Testaccio – Roman mountain of garbage Roman skyscrapers Gallic Wars Battle of Actium