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
100 records- ångström
Length · Scientific / spectroscopy · Modern scientific usage
- angula
Length · South Asia · Historical–modern
variantOne further documented definition
- arshin
Length · Russia / Eastern Europe · Medieval–modern
approx. - astronomical unit
Length · International · Modern
- Athenian / Attic stadion
Length · Ancient Greek — Attic/Athens · Classical/Hellenistic
approx.reference-only - attoparsec
Length · Various · Modern
informal - beard-second
Length · Various · Modern
variantinformalThis name has 2 documented definitions
- bema (Greek step)
Length · Ancient Greek · Classical/Hellenistic
approx.variant - cable length
Length · Maritime historical family · Historical-modern
variant - centimetre
Length · International · Modern
- chain
Length · U.S./English customary; surveying · Modern legacy + historical
- chi
Length · China / East Asia · Historical–modern
approx. - Cicero
Length
reference-only - 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. - daktylos (Greek finger)
Length · Ancient Greek · Classical/Hellenistic
variant - Delphic stadion
Length · Ancient Greek — Delphi · Classical/Hellenistic; later rebuilt track
reference-only - Didot point
Length
reference-only - digitus (Roman finger)
Length · Ancient Roman · Republic/Empire
reference-only - DTP pica
Length
- Earth radius
Length · Astronomy / geodesy · Modern scientific reference
variant - Egyptian common cubit
Length · Ancient Egypt · Antiquity
approx.One further documented definition
- Egyptian digit / finger
Length · Ancient Egyptian · Old Kingdom onward
range - Egyptian foot (ṯb.t)
Length · Ancient Egyptian · Old Kingdom attestation
disputedreference-only - Egyptian palm
Length · Ancient Egyptian · Old Kingdom onward
range - 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
- fathom
Length · U.S./English customary; maritime · Modern + historical
- foot
Length · UK / US · Modern / historical
- Fournier point
Length
variant - furlong
Length · U.S./English customary · Modern specialist + historical
- gemstone dimensions
Length · Gemological reporting · Modern
- gradus (Roman step)
Length · Ancient Roman · Republic/Empire
approx.reference-only - Greek pace
Length · Ancient Greek · Antiquity
approx.reference-only - guz / gaz
Length · South Asian / Mughal · Mughal and later regional usage
variant - Ha
Length
- hand
Length · customary; equine measurement · Current specialist / customary
- hasta
Length · South Asia · Historical–modern
variantOne further documented definition
- inch
Length · UK / US · Modern / historical
- iteru / river-measure
Length · Ancient Egyptian · Middle Kingdom onward
approx.range - ken
Length · China / East Asia · Historical–modern
- khet
Length · Ancient Egyptian · Middle Kingdom/New Kingdom and later
range - 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
- link
Length · U.S./English customary; surveying · Modern legacy + historical
- lunar distance
Length · International · Modern
approx. - metre
Length · International · Modern
- mile
Length · UK / US · Modern / historical
- millimetre
Length · International · Modern
- Nahua matl / maitl
Length · Nahua / Central Mexico · pre-Hispanic tradition documented in colonial-era Nahuatl sources
variant - nautical league
Length · Historical maritime family · Historical
variantreference-only - nautical mile
Length · UK / US · Modern / historical
- orguia (Greek fathom)
Length · Ancient Greek · Classical/Hellenistic
variant - palaiste (Greek palm)
Length · Ancient Greek · Classical/Hellenistic
variant - palmus (Roman palm)
Length · Ancient Roman · Republic/Empire and later
reference-only - Paris foot (pied du roi)
Length · France / Europe · Medieval–modern
approx. - parsec
Length · International · Modern
- passus (Roman pace)
Length · Ancient Roman · Republic/Empire
approx.reference-only - pechys (Greek cubit)
Length · Ancient Greek · Classical/Hellenistic
approx.variant - pes (Roman foot)
Length · Ancient Greece / Rome · Antiquity
approx. - plethron
Length · Ancient Greek · Classical/Hellenistic
variant - poronkusema
Length · Nordic countries / Finland · Historical
approx.informal - PostScript / DTP point
Length
- pous (Greek foot)
Length · Ancient Greek · Archaic–Hellenistic
variant - pyramid inch
Length · Various · Modern / historical
discredited - Q
Length
- remen
Length · Ancient Egyptian · New Kingdom cubit-rod attestations
disputedrange - rod
Length · U.S./English customary; surveying · Modern legacy + historical
- Roman cubitus
Length · Ancient Roman · Republic/Empire
approx.reference-only - Roman mile (mille passus)
Length · Ancient Greece / Rome · Antiquity
approx. - Roman stadium
Length · Ancient Roman · Roman Republic/Empire
approx.range - 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. - survey foot (U.S., historical)
Length · U.S. surveying legacy · Retired 2022; historical/legacy data
- TeX point
Length
- toise
Length · France / Europe · Medieval–modern
approx. - Traditional American printer’s point
Length
variant - twip
Length
- verst
Length · Russia / Eastern Europe · Medieval–modern
approx. - vitasti
Length · South Asian traditional · Ancient/medieval textual traditions
variant - yard
Length · UK / US · Modern / historical
- yojana
Length · South Asia · Historical–modern
variantOne further documented definition
Mass
53 records- ackie — Akan coastal trade
Mass · Gold Coast / Akan-European trade · late 15th–19th c. trade context
- Akan mithqal-based standard
Mass · Akan internal trade / trans-Saharan influence · historical
- 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
- drachma (mass)
Mass · Ancient Greek · Classical/Hellenistic
variant - dram (avoirdupois)
Mass · avoirdupois · Modern specialist + historical
- gemstone point
Mass · Gemstone / diamond trade · Modern standardized
- geun — Korean commodity variants
Mass · Korea · Traditional/customary; non-legal
variant - grain
Mass · avoirdupois / troy / apothecaries shared unit · Modern specialist + historical
- gram
Mass · International · Modern
- Greek mina — concept
Mass · Ancient Greek · Archaic–Hellenistic and later
variant - Greek talent
Mass · Ancient Greece / Rome · Antiquity
variantOne further documented definition
- Attic talentAncient Athens / Attic standard
- hundredweight (long)
Mass · Imperial / avoirdupois · Current specialist + historical
- hundredweight (short)
Mass · U.S. customary / avoirdupois · Current specialist
- jin (catty)
Mass · China / East Asia · Historical–modern
approx. - kilogram
Mass · International · Modern
- kite / qedet
Mass · Ancient Egyptian · New Kingdom and later
approx.range - long ton
Mass · Imperial / British customary · Current specialist + historical
- maund
Mass · South Asian · Historical; British India; modern regional survivals
variant - metric carat
Mass · International gemstone trade · Modern standardized
- mina (Mesopotamian)
Mass · Mesopotamia / Levant · Antiquity
variantThis name has 2 documented definitions
- Mesopotamian mina (later reference standard)Mesopotamia / Levant
- Early Dynastic Mesopotamian mina (range)Mesopotamia / Levant
- momme (pearl weight)
Mass · Japanese / international pearl trade · Historical-modern specialized
approx. - old carat / pre-metric carat
Mass · Historical gemstone trade · Pre-20th-century; locality-dependent
variant - ounce (avoirdupois)
Mass · UK / US · Modern / historical
- pearl grain
Mass · Natural pearl trade · Historical-modern specialized
reference-only - pennyweight
Mass · troy weight · Current specialist + historical
- pood
Mass · Russia / Eastern Europe · Medieval–modern
approx. - pound (avoirdupois)
Mass · UK / US · Modern / historical
- ratti
Mass · South Asian traditional · Ancient to modern jewelry traditions
reference-only - Roman libra
Mass · Ancient Greece / Rome · Antiquity
approx. - Roman talent
Mass · Ancient Roman · Roman-era
approx.reference-only - 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
- Mesopotamian shekel (later reference standard)Mesopotamia / Levant
- short ton
Mass · U.S. customary · Current
- Singapore kati
Mass · Singapore / historical Malaya · Customary weight retained in statute
- Singapore picul
Mass · Singapore / historical Malaya · Customary/trade weight; metrication history
- Singapore tahil
Mass · Singapore / historical Malaya · Customary weight retained in statute
- 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
- troy ounce
Mass · troy weight · Current specialist + historical
- troy pound
Mass · troy weight · Historical/specialist
- uncia (Roman ounce)
Mass · Ancient Roman · Republic/Empire
approx.reference-only
Volume
41 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
- bushel
Volume · U.S. customary dry volume · Current specialist / commercial
- butt
Volume · England / Britain · Medieval–modern
variantOne further documented definition
- English wine butt / pipe (early 17th c. nominal)England / Britain
- congius
Volume · Ancient Roman liquid measure · Republic/Empire
approx.reference-only - 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
- Egyptian hin
Volume · Ancient Egyptian · Old Kingdom onward
approx.reference-only - 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
- medimnos (Attic)
Volume · Ancient Greek — Attic dry measure · Classical/Hellenistic
approx.reference-only - metretes (Attic)
Volume · Ancient Greek — Attic liquid measure · Classical/Hellenistic
approx.reference-only - millilitre
Volume · International · Modern
- modius Italicus
Volume · Ancient Roman dry measure · Roman Italy / Empire
approx.reference-only - peck (U.S.)
Volume · U.S. customary dry volume · Current specialist + historical
- 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
- ro
Volume · Ancient Egyptian · Middle Kingdom mathematical texts onward
approx.reference-only - sextarius
Volume · Ancient Roman dry/liquid measure · Republic/Empire
approx.reference-only - tablespoon
Volume · U.S. customary culinary / volume · Current
- teaspoon
Volume · U.S. customary culinary / volume · Current
- U.S. dry pint
Volume · U.S. customary dry volume · Current specialist
- U.S. dry quart
Volume · U.S. customary dry volume · Current specialist
Area
18 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. - pyeong
Area · Korea · Legacy; culturally persistent
- square chain
Area · Survey / land measure · Historical-modern
- 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
14 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
- erg
Energy · Scientific legacy · 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
- therm
Energy · US / Europe · Modern
variant
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
Pressure
7 records- bar
Pressure · International · Modern / historical
- millimetre of mercury (conventional)
Pressure · Medical/scientific/technical · Modern
- pascal
Pressure · International · Modern
- pound per square inch (psi)
Pressure · United States · Modern
- standard atmosphere
Pressure · International · Modern
- station pressure
Pressure
- torr
Pressure · Scientific/technical · Modern/historical
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
Force
4 records- dyne
Force · Scientific legacy · Modern/historical
- kilogram-force
Force · International legacy/specialist · Modern/historical
- newton
Force · International · Modern
- pound-force
Force · US and international engineering · 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
Speed
4 records- kilometre per hour
Speed · Metric / accepted with SI · Modern
- knot
Speed · International · Modern
informal - metre per second
Speed · SI · Modern
- mile per hour
Speed · International · Modern
informal
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
Dimension one composition fraction
3 records- amount fraction
Dimension one composition fraction · SI / chemistry · Modern standardized
reference-only - mass fraction
Dimension one composition fraction · SI / chemistry / materials · Modern standardized
- volume fraction
Dimension one composition fraction · SI / chemistry / gas/liquid mixtures · Modern standardized
Linear density
3 recordsLogarithmic ratio quantity
3 recordsPower
3 records- horsepower
Power · International with multiple conventions · Modern/historical
variant - kilowatt
Power · International · Modern
- watt
Power · International · Modern
Temperature
3 records- degree Celsius
Temperature · International · Modern
- degree Fahrenheit
Temperature · International / Europe · Modern / historical
- kelvin
Temperature · International · Modern
Absorbed dose
2 recordsAcceleration
2 records- metre per second squared
Acceleration · International · Modern
- standard gravity
Acceleration · International · Modern
Architectural measurement system
2 records- Cacaxtla reconstructed modules
Architectural measurement system · Cacaxtla, Tlaxcala, Mexico · Epiclassic
approx.reference-only - Xochicalco dual measurement modules
Architectural measurement system · Xochicalco, Central Mexico · Epiclassic
approx.reference-only
Areal density
2 records- grams per square metre
Areal density · SI / textile / paper · Modern
- ounce per square yard
Areal density · U.S./Imperial textile trade · Modern trade
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
Electrical conductance
2 recordsFont relative length
2 recordsFormula based apparent temperature index
2 records- heat index
Formula based apparent temperature index
reference-only - wind chill temperature
Formula based apparent temperature index
Illuminance
2 records- foot-candle
Illuminance · US / international technical use · Modern/historical
- lux
Illuminance · International · Modern
Information
2 recordsKinematic viscosity
2 records- centistokes
Kinematic viscosity · International · Modern
- stokes
Kinematic viscosity · International · Modern
Magnetic flux
2 recordsMagnetic flux density
2 recordsMass fraction / fineness
2 records- karat (gold purity)
Mass fraction / fineness · Jewelry / precious metals · Historical-modern
- millésimal fineness
Mass fraction / fineness · Precious metals / assay · Modern
Quantity
2 recordsRadioactivity / activity of a radionuclide
2 recordsTorque
2 records- newton-metre (torque)
Torque · International · Modern
- pound-foot
Torque · United States · Modern
Amount concentration
1 records- amount-of-substance concentration
Amount concentration · SI / chemistry · Modern standardized
reference-only
Amount of substance
1 records- mole
Amount of substance · International · Modern
Architectural spacing / count
1 records- kan — Korean architectural bay
Architectural spacing / count · Korea · Traditional architecture; still descriptive
approx.reference-only
Aviation pressure setting
1 records- altimeter setting
Aviation pressure setting
Catalytic activity
1 records- katal
Catalytic activity · International · Modern
Defined dimensionless scale
1 records- Practical Salinity (PSS-78)
Defined dimensionless scale
reference-only
Defined yarn length / system family
1 records- textile hank
Defined yarn length / system family · Spinning / yarn trade · Historical-modern
variant
Dimension one density ratio
1 records- relative density
Dimension one density ratio · Chemistry / materials / hydrometry · Modern/historical
Dimensionless ratio
1 records- relative humidity
Dimensionless ratio
Dose equivalent
1 records- rem
Dose equivalent · International / US legacy · Modern/historical
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 conductivity normalized to temperature
1 records- specific conductance at 25 °C
Electrical conductivity normalized to temperature
Electrical resistance
1 records- ohm
Electrical resistance · International · Modern
Equivalent dose / radiation protection dose quantities
1 records- sievert
Equivalent dose / radiation protection dose quantities · International · Modern
Exposure to X or gamma radiation
1 records- röntgen
Exposure to X or gamma radiation · International / US legacy · Historical/legacy
Font relative spacing length
1 records- en
Font relative spacing length
Frequency ratio / interval
1 records- octave (frequency interval)
Frequency ratio / interval · Acoustics / music · Historical-modern
Frequency weighted sound level
1 records- A-weighted sound level
Frequency weighted sound level · Occupational/environmental acoustics · Modern
Geodetic reference point
1 records- geodetic bench mark
Geodetic reference point · Geodesy / surveying · Historical-modern
reference-only
Geodetic reference surface
1 records- reference ellipsoid
Geodetic reference surface · Geodesy · Modern/historical
reference-only
Gravity based reference surface
1 records- geoid
Gravity based reference surface · Geodesy / gravity · Modern scientific
reference-only
Height relative to ellipsoid
1 records- ellipsoidal height
Height relative to ellipsoid · Geodesy / GNSS · Modern
Historical laboratory factor mass
1 records- U.S. assay ton
Historical laboratory factor mass
Indentation hardness scale
1 records- Vickers hardness
Indentation hardness scale
Inductance
1 records- henry
Inductance · International · Modern
Length / advertising space depth
1 records- Agate line
Length / advertising space depth
Length / new accumulation
1 records- snowfall amount
Length / new accumulation
Length / optical attenuation
1 records- meteorological optical range
Length / optical attenuation
Length / total ground cover depth
1 records- snow depth
Length / total ground cover depth
Length used as areal depth
1 records- precipitation amount (water-equivalent depth)
Length used as areal depth
reference-only
Length with observational definition
1 records- prevailing visibility
Length with observational definition
approx.
Logarithmic chemical quantity
1 records- pH
Logarithmic chemical quantity
Logarithmic earthquake magnitude
1 records- moment magnitude
Logarithmic earthquake magnitude
Logarithmic particle size scale
1 records- phi grain-size scale
Logarithmic particle size scale
Loudness
1 records- sone
Loudness · Psychoacoustics · Modern
reference-only
Loudness level
1 records- phon
Loudness level · Psychoacoustics · Modern
approx.
Luminous flux
1 records- lumen
Luminous flux · International · Modern
Luminous intensity
1 records- candela
Luminous intensity · International · Modern
Magnetic field strength
1 records- oersted
Magnetic field strength · Scientific legacy · Modern/historical
reference-only
Mass concentration
1 records- mass concentration
Mass concentration · SI / chemistry / water quality · Modern standardized
reference-only
Mass density
1 records- mass density
Mass density · SI / physical chemistry / materials · Modern standardized
reference-only
Mass fraction / composition
1 records- ore grade (mass fraction)
Mass fraction / composition
Mass fraction expression
1 records- troy ounce per short ton ore grade
Mass fraction expression
Mass measurement system
1 records- Akan gold-weight system
Mass measurement system · Ghana / Côte d’Ivoire, Akan · c. 1400–1900 documented museum context
reference-only
Mass relationship
1 records- Akan ackie–tokoo hierarchy
Mass relationship · Gold Coast trade · historical
Mass subunit
1 records- tokoo
Mass subunit · Gold Coast / Akan-European trade · historical
variant
Measurement concept
1 records- Andean tupu / topo
Measurement concept · Andes / Inka and later Andean communities · pre-Hispanic–modern contexts
variantreference-only
Method dependent indentation hardness scale
1 records- Rockwell C hardness
Method dependent indentation hardness scale
reference-only
Molality
1 records- molality
Molality · SI / chemistry · Modern standardized
reference-only
Molar mass
1 records- molar mass
Molar mass · SI / chemistry · Modern standardized
Occupational noise exposure
1 records- NIOSH noise dose
Occupational noise exposure · Occupational hygiene · Modern
Ordinal effects/intensity scale
1 records- Modified Mercalli Intensity
Ordinal effects/intensity scale
reference-only
Ordinal observational scale
1 records- Beaufort wind force
Ordinal observational scale
reference-only
Ordinal scratch resistance scale
1 records- Mohs hardness
Ordinal scratch resistance scale
reference-only
Particle size classification
1 records- Wentworth grain-size classes
Particle size classification
reference-only
Particle size measurement / instrument opening
1 records- sieve aperture
Particle size measurement / instrument opening
Plane angle / geodetic context
1 records- minute of latitude
Plane angle / geodetic context · Geodesy/navigation · Historical-modern
variant
Risk
1 records- micromort
Risk · Various · Modern
informal
Scaled dimension one fraction expression
1 records- parts per million
Scaled dimension one fraction expression · Chemistry / environment / materials · Modern widespread
Separation between geoid and ellipsoid
1 records- geoid height
Separation between geoid and ellipsoid · Geodesy · Modern scientific
Solid angle
1 records- steradian
Solid angle · International · Modern
Solution scale / mass fraction equivalent
1 records- degrees Brix
Solution scale / mass fraction equivalent
Sound pressure level
1 records- sound pressure level
Sound pressure level · Acoustics · Modern
Specific volume
1 records- specific volume
Specific volume · SI / thermodynamics / materials · Modern standardized
reference-only
Temperature / moisture indicator
1 records- dew point temperature
Temperature / moisture indicator
reference-only
Thermodynamic activity
1 records- hydrogen-ion activity
Thermodynamic activity
reference-only
Thread density convention
1 records- thread count
Thread density convention · Bedding / woven textiles · Modern consumer/trade
Vertical reference
1 records- chart datum
Vertical reference · Hydrography/geodesy · Modern/historical
reference-only
Water depth measurement result
1 records- sounding
Water depth measurement result · Hydrography/navigation · Historical-modern
approx.reference-only
Water equivalent column depth
1 records- precipitable water
Water equivalent column depth
reference-only
Water equivalent depth
1 records- snow water equivalent
Water equivalent depth