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:

  1. 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

  1. Since late Antiquity, the Roman foot was sometimes divided into unciae comprising 12 equal parts.
  2. The ancient digit measure, however, largely dominated before the beginning of the Middle Ages.
  3. 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.
  4. 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.
  5. 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.
  6. 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.

  1. Volume: Volume can be further subcategorized as follows:
  2. 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.

  1. 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.

  1. 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

  1. 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.