Units

Wikipedia: https://en.wikipedia.org/wiki/Units_of_measurement
Wikipedia: https://en.wikipedia.org/wiki/System_of_measurement

Mass noun

Wikipedia: https://en.wikipedia.org/wiki/Mass_noun

RDF and Units

Units of measurement can be expressed with RDF, RDFS, and OWL.

CSVW and Units

See: CSVW, Tool Support for Units

Tool Support for Units

Spreadsheet tools:

  • Specify units in each column heading (e.g. "time [[s]]","speed [[m/s]]")

  • Extra column per column for units (e.g. "time","time unit","speed","speed unit")

  • CSVW: Columns have URIs, which are objects that can have subjects and predicates (for XSD types; metadata (author, date, rdfs:label "time"@en"), and possibly units of measure)

Unit and/or precision-aware calculations:

Storage formats:

  • [ ] Spreadsheet formats do not have unit of measure support.

  • CSV does not have unit of measure support.

  • JSON does not have unit of measure support.

  • RDF vocabularies support units of measure:

    • CSVW supports units of measure.

    • JSON-LD supports units of measure.

Binary Prefixes

Table of Binary Prefixes (adapted from: https://en.wikipedia.org/wiki/Binary_prefix)

Text

Symbol

Scalar (base 10)

Scalar (base 1000)

Scalar (base 1e1)

kilo

k

1000

1000**1

1e3

mega

M

1000000

1000**2

1e6

giga

G

1000000000

1000**3

1e9

tera

T

1000000000000

1000**4

1e12

peta

P

1000000000000000

1000**5

1e15

exa

E

1000000000000000000

1000**6

1e18

zetta

Z

1000000000000000000000

1000**7

1e21

yotta

Y

1000000000000000000000000

1000**8

1e24

See also: SI Prefixes

Metric System

Wikipedia: https://en.wikipedia.org/wiki/Metric_system
Wikipedia: https://en.wikipedia.org/wiki/Outline_of_the_metric_system

SI Units

Wikipedia: https://en.wikipedia.org/wiki/International_System_of_Units
Wikipedia: https://en.wikipedia.org/wiki/SI_base_unit
Wikipedia: https://en.wikipedia.org/wiki/SI_derived_unit

SI Units (International System of Units) are the standard units of measurement for almost every country on Earth.

SI Base Units

Wikipedia: https://en.wikipedia.org/wiki/International_System_of_Units#Base_units

SI Prefixes

Wikipedia: https://en.wikipedia.org/wiki/Metric_prefix
Table of SI Prefixes (adapted from: https://en.wikipedia.org/wiki/Template:Common_metric_prefixes and https://en.wikipedia.org/wiki/Binary_prefix)

Text

Symbol

Scaling Factor

Scaling Factor (e)

pico

p

0.000000000001

1e-12

nano

n

0.000000001

1e-9

micro

μ

0.000001

1e-6

milli

m

0.001

1e-3

centi

c

0.01

1e-2

deci

d

0.1

1e-1

(none)

(none)

1

1e0

deca

da

10

1e1

hecto

h

100

1e2

kilo

k

1000

1e3

mega

M

1000000

1e6

giga

G

1000000000

1e9

tera

T

1000000000000

1e12

peta

P

1000000000000000

1e15

exa

E

1000000000000000000

1e18

zetta

Z

1000000000000000000000

1e21

yotta

Y

1000000000000000000000000

1e24

See also: Binary Prefixes

SI Distance Units

metre

Wikipedia: https://en.wikipedia.org/wiki/Metre
Wikipedia: https://en.wikipedia.org/wiki/Meter
Abbr: m

The metre is the length of the path travelled by light in vacuum during a time interval of 1/299792458 of a second

SI Volume Units

litre

Wikipedia: https://en.wikipedia.org/wiki/Litre
Abbr: L

SI Mass Units

kilogram

Wikipedia: https://en.wikipedia.org/wiki/Kilogram
gram
Wikipedia: https://en.wikipedia.org/wiki/Gram
Abbr: g

SI Time Units

second

Wikipedia: https://en.wikipedia.org/wiki/Second #TODO
Abbr: sec
Abbr: s
microsecond
Wikipedia: https://en.wikipedia.org/wiki/Microsecond #TODO
Abbr: TODO
millisecond
Wikipedia: https://en.wikipedia.org/wiki/Millisecond #TODO
Abbr: ms
minute
Wikipedia: https://en.wikipedia.org/wiki/Minute
Abbr: min
Abbr: m
hour
Wikipedia: https://en.wikipedia.org/wiki/Hour
Abbr: hr
Abbr: hrs
Abbr: h
day
Wikipedia: https://en.wikipedia.org/wiki/Day
Abbr: d

  • Conversion: 1 day == 24 hours

  • Conversion: 1 day == 1440 minutes

  • Conversion: 1 day == 86400 seconds

  • Rotational definition: 1 day == one complete planetary rotation

week
Wikipedia: https://en.wikipedia.org/wiki/Week
Abbr: wk
Abbr: wks
Abbr: w
month
Wikipedia: https://en.wikipedia.org/wiki/Month
Abbr: mon
Abbr: mons
Abbr: m

  • A month contains either 28 (Feb; 29 on a leap year), 30, or 31 days.

  • https://en.wikipedia.org/wiki/Thirty_days_hath_September

  • Two hands of knuckles with peaks and valleys together:

    • start with an outside knuckle

    • up (peak; knuckle) – 31 days

    • down (peak; knuckle) – 30 day (except for February, which has 28/29)

year
Wikipedia: https://en.wikipedia.org/wiki/Year
Abbr: yr
Abbr: yrs
Abbr: y

  • Conversion: 1 year == 365.25 days (1 leap day/4.0)

  • Conversion: 1 year == 365 days

  • Conversion: 1 year == 8760 hours

  • Conversion: 1 year == 525600 minutes

  • Conversion: 1 year == 31536000 seconds

  • Rotational definition: 1 year == 1 complete revolution around our singular planetary star: the sun.

SI Frequency Units

hertz

Wikipedia: https://en.wikipedia.org/wiki/Hertz
Abbr: Hz

  • TODO: cycles per time

  • TODO: em.py

SI Electric Current Units

ampere

Wikipedia: https://en.wikipedia.org/wiki/Ampere
Abbr: A # TODO
Abbr: amp

# TODO

volt

Wikipedia: https://en.wikipedia.org/wiki/Volt
Abbr: V # TODO

# TODO frequency / current relation

SI Power Units

joule

Wikipedia: https://en.wikipedia.org/wiki/Joule

watt

Wikipedia: https://en.wikipedia.org/wiki/Watt

SI Temperature Units

celsius

Wikipedia: https://en.wikipedia.org/wiki/Celsius
Abbr: C

  • Water (H2O) freezes at 0 degrees celsius.

  • Water (H20) boils at 100 degrees celsius.

  • [ ] celsius / kelvin relation

kelvin

Wikipedia: https://en.wikipedia.org/wiki/Kelvin
Abbr: K

SI Amount Units

mole

Wikipedia: https://en.wikipedia.org/wiki/Mole_(unit)
Abbr: mol

SI Luminous Intensity Units

candela

Wikipedia: https://en.wikipedia.org/wiki/Candela
Abbr: cd

SI Data Units

bit

Wikipedia: https://en.wikipedia.org/wiki/Bit
Abbr: b

A bit can be 1 or 0.

  • A bit may indicate set containment (e.g. True or False, Black or White) [Set Theory]

  • A bit may be part of an ordered set of bits which ascribe left-to-right (little endian) or right-to-left (big endian) place values to each binary digit:

    1 2 4 8   # little endian
0 1 0 1   # == 0 + 2 + 0 + 8 == 9 (base 10)

8 4 2 1   # big endian
0 1 0 1   # == 0 + 4 + 0 + 1 == 5 (base 10)

  • See also: Information Theory > Shannon bit (Shannon entropy)

byte

Wikipedia: https://en.wikipedia.org/wiki/Byte
Abbr: B

  • Conversion: 1 byte == 8 bits

  • Storage vendors use powers of ten (e.g. MB, GB, TB) to describe storage capacity; and also binary prefixes (kilo, mega, giga, tera, peta, exa, zetta).

  • Many/most software programs use powers of two and binary prefixes (e.g. MiB, GiB, TiB) to describe e.g. partition and file sizes.

  • On-disk file sizes are often larger than the file content because of file allocation tables, redundancy, block size and allocation; but may be smaller after compression/deduplication.

Table of Bytes and Binary Prefixes

unit

derivation

value

nibble

2**2 bits

4 bits

byte

2**3 bits

8 bits

octet

2**3 bits

8 bits

word size

CPU

register width

(in bits)

8+, 16, 24, 32, 64 bits

32 bits (x86, ARM)

64 bits (x86_64, ARM 64)

kibibyte (KiB)

2**10 bytes

1024**1 bytes

1024 bytes

kiloyte (KB)

1e3 bytes

1000**1 bytes

1000 bytes

mebibyte (MiB)

2**20 bytes

1024**2 bytes

1048576 bytes

megabyte (MB)

1e6 bytes

1000**2 bytes

1000000 bytes

gibibyte (GiB)

2**30 bytes

1024**3 bytes

1073741824 bytes

gigabyte (GB)

1e9 bytes

1000**3 bytes

1000000000 bytes

tebibyte (TiB)

2**40 bytes

1024**4 bytes

1099511627776 bytes

terabyte (TB)

1e12 bytes

1000**4 bytes

1000000000000 bytes

pebibyte (PiB)

2**50 bytes

1024**5 bytes

1125899906842624 bytes

petabyte (PB)

1e15 bytes

1000**5 bytes

1000000000000000 bytes

exbibyte (EiB)

2**60 bytes

1024**6 bytes

1152921504606846976 bytes

exabyte (EB)

1e18 bytes

1000**6 bytes

1000000000000000000 bytes

zebibyte (ZiB)

2**70 bytes

1024**7 bytes

1180591620717411303424 bytes

zettabyte (ZB)

1e21 bytes

1000**7 bytes

1000000000000000000000 bytes

yobibyte (YiB)

2**80 bytes

1024**8 bytes

1208925819614629174706176 bytes

yottabyte (YB)

1e21 bytes

1000**8 bytes

1000000000000000000000000 bytes

Imperial units

Wikipedia: https://en.wikipedia.org/wiki/Imperial_units
Wikipedia: https://en.wikipedia.org/wiki/English_units

Imperial units may refer to either English units (ended in 1824) or US customary units (e.g. gram, ounce, gallon, pound, foot, mile).

Imperial Distance Units

inch

Wikipedia: https://en.wikipedia.org/wiki/Inch
Abbr: in
yard
Wikipedia: https://en.wikipedia.org/wiki/Foot
Abbr: yd
mile
Wikipedia: https://en.wikipedia.org/wiki/Mile
Abbr: mi
Abbr: m

Imperial Volume Units

teaspoon

Wikipedia: https://en.wikipedia.org/wiki/Teaspoon
Abbr: t
Abbr: tsp.

dram

Wikipedia: https://en.wikipedia.org/wiki/Dram_(unit)

tablespoon

Wikipedia: https://en.wikipedia.org/wiki/Tablespoon
Abbr: T
Abbr: Tbsp.

cup

Wikipedia: https://en.wikipedia.org/wiki/Cup_(unit)
Abbr: c

fluid ounce

Wikipedia: https://en.wikipedia.org/wiki/Fluid_ounce
Abbr: fl oz
Abbr: oz

pint

Wikipedia: https://en.wikipedia.org/wiki/Pint
Abbr: pt

quart

Wikipedia: https://en.wikipedia.org/wiki/Quart
Abbr: qt

gallon

Wikipedia: https://en.wikipedia.org/wiki/Gallon
Abbr: gal

keg

Wikipedia: https://en.wikipedia.org/wiki/Keg

Imperial Mass Units

gram

Wikipedia: https://en.wikipedia.org/wiki/Gram
Abbr: g

ounce

Wikipedia: https://en.wikipedia.org/wiki/Ounce
Abbr: oz

pound

Wikipedia: https://en.wikipedia.org/wiki/Pound
Abbr: lb
Abbr: lbm

ton

Wikipedia: https://en.wikipedia.org/wiki/Ton

  • Conversion: 1 ton == 2000 pounds

  • Conversion: 1 kilo- ton == 1000 tons

  • Colloqial: half ton truck refers to a minimum towing or hauling capacity; not the curb weight of a vehicle.

  • Conversion: 1 tonne (metric ton) == 1000 kg == 2204 pound

  • Conversion: 1 long ton == 2240 pound

  • Conversion: 1 short ton == 2000 pound

US customary units

Wikipedia: https://en.wikipedia.org/wiki/United_States_customary_units

Common US Fluid Conversions:

Industry Units

Freight

Fuel