Units of Measurements

Units of Measurements

The units of measurement are the units that are used to represent physical quantities.

We use different measurements units including the traditional units, the metric system of units, the imperial system of units and US customary units.

The metric system is also known as the International System of Units (called the SI units).

The seven SI base units, which are comprised of:

  • Length – centimetre (cm), metre (m),  kilometre (km)
  • Area  – square centimetre (cm2), square metre (m2), square kilometre (km2)
  • Volume  – cubic centimetre (cm3), cubic metre (m3)
  • Capacity – millilitre (mL), litre (L)
  • Time – second (s)
  • Digital information – byte (B)
  • Temperature – Kelvin scale (symbol K), Celsius scale (symbol ºC) or Fahrenheit scale (ºF)
  • Mass – gram (g), kilogram (kg), tonne (t)
  • Amount of substance – mole (mole)
  • Electric current – ampere (A)
  • Luminous intensity – candela (cd)
  • Mass – kilogram (kg)

Metric Units  –  Length

10 millimetres = 1 centimetre, cm
10 centimetres = 1 decimetre, dm
10 decimetres = 1 metre, m
10 metres = 1 decametre, dam
10 decametres = 1 hectometre, hm
10 hectometres = 1 kilometre, km
1000 metres = 1 kilometre, km

Metric Units – Area

1 square metre = 10 000 square centimetres, cm2
1 hectare = 10 000 square metres, m2
1 square kilometre = 100 hectares, ha
1 square metre = 100 square decimetre, dm2
1 square decimetre = 100 square centimetre, cm2
1 square centimetre = 100 square millimetre, mm2

Metric Units  –  Volume

1000 cubic millimetres = 1 cubic centimetre, cm3
1000 cubic centimetres = 1 cubic decimetre, dm3
1,000 cubic decimetres = 1 cubic metre, m3
1,000,000 cubic centimetres = 1 cubic metre, m3
1 litre, l = 1 cubic decimetre, dm3

Metric Units – Mass

1000 milligrams = 1 gram, g
1000 grams = 1 kilogram, kg
1000 kilograms = 1 tonne, t

Metric Units ~ Temperature

Celsius, ºC 

Metric Units – Capacity  (fluid volume)

10 millilitres = 1 centilitre, cl or cL
10 centilitres = 1 decilitre, dl or dL
10 decilitres = 1 litre, l or L
1000 litres = 1 kilolitre, kl or kL
1,000,000 litres = 1 megalitre, Ml or ML
1,000,000,000 litres = 1 gigalitre, Gl or GL
1,000,000,000,000 litres = cubic kilometre = 1 teralitre, Tl or TL

Units of time

seconds < minutes < days < weeks < months < years

1 minute = 60 seconds

1 hour = 60 minutes

1 hour = 3600 seconds

1 day = 24 hours

1 week = 7 days

1 mounth = 4 weeks

1 year = 12 months

10 years = 1 decade

100 years = 1 century

1000 years = 1 millennium

1 month can have 28, 29, 30 or 31 days depending upon the month.

1 year = 365 days

1 leap year = 366 days

1 year has 52 weeks and one day whereas a leap year has 52 weeks and two days.

Multiple-byte units – Unit system

More than one system exists to define unit multiples based on the byte.
The byte is a unit of digital information that most commonly consists of eight bits. 
Some systems are based on powers of 10, following the International System of Units (SI), which defines for example the prefix kilo as 1000 (103).

Value
1000
10002
10003
10004
10005

Metric
kilobyte, kB
megabyte, MB
gigabyte, GB
terabyte, TB
petabyte,  PB

Value
10006
10007
10008
10009
100010

Metric
exabyte, EB
zettabyte, ZB
yottabyte, YB
ronnabyte, RB
quettabyte, QB

 1 kilobyte (kB) = 1000 byte (B)
1 megabyte (MB) = 1000 kilobyte (kB)
1 gigabyte (GB) = 1000 megabyte
1 terabyte (TB)  = 1000 gigabyte (GB)

Other systems are based on powers of 2.

  • 1 kB (kilobyte) = 1024 (210) byte.
  • 1 MB (megabyte) = 1024 kB = 1 048 576 byte.
  • 1 GB (gigabyte) = 1024 MB = 1 073 741 824 byte.
  • 1 TB (terabyte) = 1024 GB = 1 099 511 627 776 byte.
  • 1 PB (petabyte) = 1024 TB = 1 125 899 906 842 624 byte.
  • 1 EB (eksabyte) = 1024 PB = 1 152 921 504 606 846 976 byte.
  • 1 ZB (zetabyte) = 1024 EB = 1 180 591 620 717 411 303 424 byte.
  • 1 YB (jotabyte) = 1024 ZB = 1 208 925 819 614 629 174 706 176 byte.

https://www.transum.org/Maths/Activity/Units/Default.asp?Level=1