Units

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

SI Prefixes

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

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

SI Mass Units

kilogram

gram

SI Time Units

second

Abbr: sec
Abbr: s
microsecond
Abbr: TODO
millisecond
Abbr: ms
minute
Abbr: min
Abbr: m
hour
Abbr: hr
Abbr: hrs
Abbr: h
day
  • Conversion: 1 day == 24 hours

  • Conversion: 1 day == 1440 minutes

  • Conversion: 1 day == 86400 seconds

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

week
Abbr: wk
Abbr: wks
Abbr: w
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
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

  • TODO: cycles per time

  • TODO: em.py

SI Electric Current Units

ampere

Abbr: A # TODO
Abbr: amp

# TODO

volt

Abbr: V # TODO

# TODO frequency / current relation

SI Power Units

SI Temperature Units

celsius

  • Water (H2O) freezes at 0 degrees celsius.

  • Water (H20) boils at 100 degrees celsius.

  • [ ] celsius / kelvin relation

kelvin

SI Amount Units

SI Luminous Intensity Units

candela

SI Data Units

bit

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

  • 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

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

yard
mile
Abbr: mi
Abbr: m

Imperial Volume Units

teaspoon

Abbr: t
Abbr: tsp.

dram

tablespoon

Abbr: T
Abbr: Tbsp.

fluid ounce

Abbr: fl oz
Abbr: oz

pint

quart

gallon

keg

Imperial Mass Units

gram

ounce

pound

Abbr: lb
Abbr: lbm

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

Common US Fluid Conversions:

Industry Units

Freight

Fuel