The ancient Roman Measurements came to be developed on the lines of the Hellenic with Egyptian, Hebrew, and Mesopotamian influences. The Roman units were comparatively consistent and have been well documented. The different units of Roman Measurements were as follows:
- Length – Modern scientists have found the Roman foot to be 16⁄28 of the Nippur cubit.
Roman unit
Latin name
Feet
Equivalence
one digit
digitus
1⁄16
18.5 mm
one Inch
uncia
1⁄12
24.6 mm
one palm
palms
1⁄4
74 mm
one foot
pes
1
29.6 cm
one cubit
cubitus
1 1⁄2
44.4 cm
one step
gradus
2 1⁄2
0.74 m
one pace
passus
5
1.48 m
one perch
Pertica
10
2.96 m
one arpent
actus
120
35.5 m
one stadium
stadium
625
185 m
one mile
mille Passuum (Milliarium)
5000
1.48 km
one league
Leuga
7500
2.2225 km
- Since late Antiquity, the Roman foot was sometimes divided into unciae comprising 12 equal parts.
- The ancient digit measure, however, largely dominated before the beginning of the Middle Ages.
- The value of the historical Roman foot scientifically obtained through modern statistical methods is 296.2 mm ± 0.5 mm, or about (296.2 ± 0.17%) mm. The table above is based on this value but rounded to the millimeter precision for the foot.
- The widely accepted ratio between the Roman foot and the English foot is 36:35. That is 36 Roman feet to 35 English feet, making the Roman foot slightly shorter than its modern equivalent. The latter one is 16/28 Mesopotamian cubit and the ratio between this one and the Roman cubit is 20:24. If the present English foot is taken as for reference, the Roman foot should be 296 1/3 mm or approximately 11.65 English inches. That is within the margin obtained by R.C.A. Rottlander.
- A Roman foot can be visualized as being approximately equal to the height of an A4 Sheet of paper (297 mm). This comparison, although descriptive, is +0.27% out of the range given above.
- Area – the unit for measuring area were as follows:
Roman unit
Latin name
Acres
Equivalence
one square foot
pes quadratus
1⁄14 400
~ 876 cm²
one square perch
Scripulum
1⁄144
~ 8.76 m²
one aune of furrows
actus minimus
1⁄30
~ 42 m²
one rood
Clima
1⁄4
~ 315 m²
one acre
actus quadratus
also known as acnua
1
~ 1260 m²
one yoke
iugerum
2
~ 2520 m²
one morn
heredium
4
~ 5040 m²
one centurie
centuria
400
~ 50.5 ha
one “quadruplex”
saltus
1600
~ 201.9 ha
The Roman acre is the squared Roman arpent, 120 pedes by 120 pedes. This equals 14 400 square feet or about 0.126 hectares. Further, the Romans also had a unit area called a Quinaria, which was used to measure the cross-sectional area of pipes. One Quinaria was considered to be roughly 4.2 cm².
- Volume: Volume can be further subcategorized as follows:
- Liquid measures: The units for measuring liquids were as follows:
Roman unit
Latin name
Sesters
Equivalent
one spoonful
ligula
1⁄48
~ 11.25 ml
one dose
Cyathus
1⁄12
~ 45 ml
one sixth-sester
sextans
1⁄6
~ 90 ml
one third-sester
Triens
1⁄3
~ 180 ml
one half-sester
hemina
1⁄2
~ 270 ml
one double third-sester
choenix
2⁄3
~ 360 ml
one sester
sextarius
1
~ 540 ml
one congius
congius
6
~ 3.25 l
one urn
urna
24
~ 13 l
one jar
amphora
48
~ 26 l
one hose
culleus
960
~ 520 l
The Roman jar, which was called as “amphora quadrantal” was the cubic foot. The congius was half-a-foot cubed. The Roman Sester was a sixth of a congius.
- Dry measures – The units of Roman Measurements for dry objects were:
Roman unit
Latin name
Pecks
Equivalence
one drawing-spoon
Acetabulum
1⁄128
~ 67.5 ml
one quarter-sester
quartarius
1⁄64
~ 135 ml
one half-sester
hemina
1⁄32
~ 270 ml
one sester
sextarius
1⁄16
~ 540 ml
one gallon
semodius
1⁄2
~ 4 1⁄3 l
one peck
modius
1
~ 8 2⁄3 l
one bushel
quadrantal
3
~ 26 l
Like the jar, the Roman bushel or “quadrantal” was one cubic foot. It is almost 26.027 liters. One-third of a Quandrantal was a Roman peck.
- Mass: The units for the computation of mass of any object were same as that of coins which are as follows:
Roman unit
Latin name
Drachms
Equivalence
one chalcus
chalcus
1 / 48
~ 71 mg
one siliqua
siliqua
1 / 18
~ 189⅓ mg
one obolus
obolus
1 / 6
~ 0.568 g
one scruple
scrupulum
1 / 3
~ 1.136 g
one dram
drachma
1
~ 3.408 g
one shekel
sicilicus
2
~ 6.816 g
one ounce
uncia
8
~ 27.264 g
one pound
libra
96
~ 327.168 g
one mine
mina
128
~ 436.224 g
The Roman pound is exactly three-quarters of the Greek mine.
Thus the Greek and Roman drachm are related by the ratio 32 to 25.
All the multiples of the Roman ounce have their own names
1 ounce =
uncia
ounce
1.5 ounce =
sescunx
ounce-and-a-half
2 ounces =
sextans
sixth of an as
3 ounces =
quadrans
quarter of an as
4 ounces =
triens
third of an as
5 ounces =
quincunx
five ounces
6 ounces =
semis
half an as
7 ounces =
septunx
seven ounces
8 ounces =
bes
twice (twice a triens)
9 ounces =
dodrans
an as, less a quarter
10 ounces =
dextans
an as, less a sixth
11 ounces =
deunx
an as, less an ounce
One and a half ounces was called by Romans “Sescuncia”. Some of these Nouns were used to designate Roman bronze coins
- Time: The complicated Roman calendar was replaced by the Julian Calendar in 45 BC. In the Julian calendar, an ordinary year was 365 days long, a leap year was 366 days long, and every fourth year is a leap year. The year number was initially the count of years since the founding of Rome, “Ab Urbe Condita” in 753 BC. The year numbering was later changed to the Anno Domini count.
A pace or double-pace or passus was a measure of distance used in Ancient Rome. It was the measure of a full stride from the position of the heel when it was raised from the ground to the point the same heel is set down again at the end of the step.
Thus, a distance can be “paced off” by counting each time the same heel touches the ground, or, in other words, every other step. In Rome, this unit was standardized as two gradus or five Roman feet (about 1.48 meters or 58.1 English inches).
There are 1000 passes in one mile, and a mile was sometimes referred to as a mile passes. A pace in modern terminology can be taken as being a single pace rather than a double pace. It has no formal definition but is taken as being around 30 inches.