The library
Explore measurement units
The same collection, seen from five directions. Nothing here is filtered by how respectable a unit is — only by what it measures, who used it, and how sure the evidence lets us be.
Length
53 records- angula
Length · South Asia · Historical–modern
variantOne further documented definition
- arshin
Length · Russia / Eastern Europe · Medieval–modern
approx. - astronomical unit
Length · International · Modern
- attoparsec
Length · Various · Modern
informal - beard-second
Length · Various · Modern
variantinformalThis name has 2 documented definitions
- centimetre
Length · International · Modern
- chi
Length · China / East Asia · Historical–modern
approx. - cubit (biblical)
Length · Mesopotamia / Levant · Antiquity
variantThis name has 2 documented definitions
- Biblical ordinary cubit (reference reconstruction)Mesopotamia / Levant
- Ezekiel long cubitMesopotamia / Levant
- cun
Length · China / East Asia · Historical–modern
approx. - Egyptian common cubit
Length · Ancient Egypt · Antiquity
approx.One further documented definition
- Egyptian royal cubit
Length · Ancient Egypt · Antiquity
approx.One further documented definition
- Egyptian royal cubit (reference reconstruction)Ancient Egypt
- ell
Length · Europe · Historical
variantThis name has 3 documented definitions
- Flemish ellEurope
- Scottish ellEurope
- English ellEurope
- foot
Length · UK / US · Modern / historical
- hasta
Length · South Asia · Historical–modern
variantOne further documented definition
- inch
Length · UK / US · Modern / historical
- ken
Length · China / East Asia · Historical–modern
- kilometre
Length · International · Modern
- kivenheitto
Length · Nordic countries / Finland · Historical
informalreference-only - kos
Length · South Asia · Historical–modern
variantOne further documented definition
- li (Chinese distance)
Length · China / East Asia · Historical–modern
approx. - light-year
Length · International · Modern
- lunar distance
Length · International · Modern
approx. - metre
Length · International · Modern
- mile
Length · UK / US · Modern / historical
- millimetre
Length · International · Modern
- nautical mile
Length · UK / US · Modern / historical
- Paris foot (pied du roi)
Length · France / Europe · Medieval–modern
approx. - parsec
Length · International · Modern
- pes (Roman foot)
Length · Ancient Greece / Rome · Antiquity
approx. - poronkusema
Length · Nordic countries / Finland · Historical
approx.informal - pyramid inch
Length · Various · Modern / historical
discredited - Roman mile (mille passus)
Length · Ancient Greece / Rome · Antiquity
approx. - shaku
Length · China / East Asia · Historical–modern
- Sheppey
Length · Various · Modern
approx.informal - smoot
Length · Various · Modern
approx.informal - stadion (Olympia)
Length · Ancient Greece / Rome · Antiquity
approx. - toise
Length · France / Europe · Medieval–modern
approx. - verst
Length · Russia / Eastern Europe · Medieval–modern
approx. - yard
Length · UK / US · Modern / historical
- yojana
Length · South Asia · Historical–modern
variantOne further documented definition
Volume
28 records- acre-foot
Volume · United States · Modern
- amphora quadrantal
Volume · Ancient Greece / Rome · Antiquity
approx. - bath (biblical volume)
Volume · Mesopotamia / Levant · Antiquity
variantdisputedOne further documented definition
- Biblical bath (common scholarly reconstruction)Mesopotamia / Levant
- butt
Volume · England / Britain · Medieval–modern
variantOne further documented definition
- English wine butt / pipe (early 17th c. nominal)England / Britain
- cubic foot
Volume · US / UK · Modern
- cubic inch
Volume · US / UK · Modern
- cubic metre
Volume · International · Modern
- cubic yard
Volume · US / UK · Modern
- cup (US customary)
Volume · UK / US · Modern / historical
- ephah
Volume · Mesopotamia / Levant · Antiquity
variantOne further documented definition
- Biblical ephah (common scholarly reconstruction)Mesopotamia / Levant
- fluid ounce (Imperial)
Volume · UK / US · Modern / historical
- fluid ounce (US)
Volume · UK / US · Modern / historical
- gallon (Imperial)
Volume · UK / US · Modern / historical
- gallon (US liquid)
Volume · UK / US · Modern / historical
- hekat
Volume · Ancient Egypt · Antiquity
approx.One further documented definition
- Egyptian hekat (Old/Middle Kingdom reference)Ancient Egypt
- hogshead
Volume · England / Britain · Medieval–modern
variantOne further documented definition
- English wine hogshead (early 17th c. nominal)England / Britain
- koku
Volume · China / East Asia · Historical–modern
- litre
Volume · International · Modern
- millilitre
Volume · International · Modern
- pint (Imperial)
Volume · UK / US · Modern / historical
- pint (US liquid)
Volume · UK / US · Modern / historical
- quart (Imperial)
Volume · UK / US · Modern / historical
- quart (US liquid)
Volume · UK / US · Modern / historical
Mass
26 records- dalton / unified atomic mass unit
Mass · International · Modern
approx. - deben
Mass · Ancient Egypt · Antiquity
variantThis name has 3 documented definitions
- Egyptian deben (New Kingdom standard)Ancient Egypt
- Egyptian gold deben (Old/Middle Kingdom range)Ancient Egypt
- Egyptian copper deben (Old/Middle Kingdom reference)Ancient Egypt
- gram
Mass · International · Modern
- Greek talent
Mass · Ancient Greece / Rome · Antiquity
variantOne further documented definition
- Attic talentAncient Athens / Attic standard
- jin (catty)
Mass · China / East Asia · Historical–modern
approx. - kilogram
Mass · International · Modern
- Mesopotamian shekel (later reference standard)
Mass · Mesopotamia / Levant · Antiquity
approx. - ounce (avoirdupois)
Mass · UK / US · Modern / historical
- pood
Mass · Russia / Eastern Europe · Medieval–modern
approx. - pound (avoirdupois)
Mass · UK / US · Modern / historical
- Roman libra
Mass · Ancient Greece / Rome · Antiquity
approx. - seer
Mass · South Asia · Historical–modern
variantOne further documented definition
- British Indian standard seer (1939)British India
- shekel (ancient mass)
Mass · Mesopotamia / Levant · Antiquity
variantOne further documented definition
- mina (Mesopotamian)Mesopotamia / Levant
- stone
Mass · UK / US · Modern / historical
- talent (Mesopotamian)
Mass · Mesopotamia / Levant · Antiquity
variantOne further documented definition
- Mesopotamian talent (later reference standard)Mesopotamia / Levant
- tola
Mass · South Asia · Historical–modern
approx. - tonne
Mass · International · Modern
Area
16 records- acre
Area · UK / US · Modern / historical
- barn
Area · Various · Modern
- bigha
Area · South Asia · Historical–modern
variantOne further documented definition
- Rohtak government bigha (gazetteer reference)Rohtak, India
- dunam
Area · Europe · Historical
variantThis name has 2 documented definitions
- hectare
Area · International · Modern
- mu
Area · China / East Asia · Historical–modern
approx. - square foot
Area · UK / US · Modern / historical
- square inch
Area · US / UK · Modern
- square kilometre
Area · International · Modern
- square metre
Area · International · Modern
- square mile
Area · UK / US · Modern / historical
- square yard
Area · UK / US · Modern / historical
- tsubo
Area · China / East Asia · Historical–modern
Energy
12 records- British thermal unit
Energy · International · Modern / historical
variantThis name has 2 documented definitions
- British thermal unit (thermochemical)International
- British thermal unit (International Table)International
- calorie
Energy · International · Modern / historical
variantThis name has 2 documented definitions
- calorie (thermochemical)International
- calorie (International Table)International
- electronvolt
Energy · International · Modern / historical
- joule
Energy · International · Modern
- kilocalorie
Energy · International · Modern / historical
variantThis name has 2 documented definitions
- kilocalorie (thermochemical)International
- kilocalorie (International Table)International
- kilowatt-hour
Energy · International · Modern
Time
10 records- day
Time · International · Mixed
- hour
Time · International · Mixed
- jiffy (physics usage)
Time · International · Mixed
approx.informalOne further documented definition
- Light-centimetre jiffyInternational
- minute
Time · International · Mixed
- Planck time
Time · International · Mixed
approx. - Scaramucci
Time · International · Mixed
informal - second
Time · International · Modern
- shake
Time · International · Mixed
informal - week
Time · International · Mixed
Frequency
5 records- gigahertz
Frequency · International · Modern
- hertz
Frequency · International · Modern
- kilohertz
Frequency · International · Modern
- megahertz
Frequency · International · Modern
- revolution per minute (rpm)
Frequency · International · Modern
Fuel efficiency
4 records- kilometre per litre
Fuel efficiency · International · Modern
- litre per 100 kilometres
Fuel efficiency · International · Modern
- mile per Imperial gallon
Fuel efficiency · United Kingdom / Commonwealth · Modern
- mile per US gallon
Fuel efficiency · United States · Modern
Angle
4 records- arcminute
Angle · International · Modern
- arcsecond
Angle · International · Modern
- degree (angle)
Angle · International · Modern
- radian
Angle · International · Modern
Density
3 records- gram per cubic centimetre
Density · International · Modern
- kilogram per cubic metre
Density · International · Modern
- pound per cubic foot
Density · US / UK · Modern
Pressure
3 records- bar
Pressure · International · Modern / historical
- pascal
Pressure · International · Modern
- pound per square inch (psi)
Pressure · United States · Modern
Temperature
3 records- degree Celsius
Temperature · International · Modern
- degree Fahrenheit
Temperature · International / Europe · Modern / historical
- kelvin
Temperature · International · Modern
Acceleration
2 records- metre per second squared
Acceleration · International · Modern
- standard gravity
Acceleration · International · Modern
Viscosity
2 records- centipoise
Viscosity · International · Modern
- pascal-second
Viscosity · International · Modern
Electric charge
2 records- ampere-hour
Electric charge · International · Modern
- coulomb
Electric charge · International · Modern
Information
2 recordsKinematic viscosity
2 records- centistokes
Kinematic viscosity · International · Modern
- stokes
Kinematic viscosity · International · Modern
Quantity
2 recordsPower
2 recordsSpeed
2 records- knot
Speed · International · Modern
informal - mile per hour
Speed · International · Modern
informal
Torque
2 records- newton-metre (torque)
Torque · International · Modern
- pound-foot
Torque · United States · Modern
Electric current
1 records- ampere
Electric current · International · Modern
Electric potential
1 records- volt
Electric potential · International · Modern
Electrical capacitance
1 records- farad
Electrical capacitance · International · Modern
Electrical conductance
1 records- siemens
Electrical conductance · International · Modern
Electrical resistance
1 records- ohm
Electrical resistance · International · Modern
Force
1 records- newton
Force · International · Modern
Inductance
1 records- henry
Inductance · International · Modern
Magnetic flux
1 records- weber
Magnetic flux · International · Modern
Magnetic flux density
1 records- tesla
Magnetic flux density · International · Modern
Risk
1 records- micromort
Risk · Various · Modern
informal
Solid angle
1 records- steradian
Solid angle · International · Modern