Entropy and Information Units for Some Digital and Encoding Systems
Base
Unit
Logarithm
Full Name
Character Set
in bit
References
2
bit
log2
binary digit, binary unit
0,1 (or b,w; or +,-, etc.)
1
C. E. Shannon
e
nat
ln
natural digit, natural unit
-
1.44
 Natural logarithms have a base of  e = 2.71828
http://en.wikipedia.org/wiki/Nat (information)
e
e.u. : cal/(mol. K)
ln
(thermodynamic) entropy unit
(atoms, modes of molecular motion, ...)
1.44 k
k is the Boltzmann constant
3
 
 log3
 Ternary
0,1,2 (or , etc.)
1.58
 
 
log4
 
0,1,2,3 (G,C,A,T in DNA)
2
 
5
 
 log5
 Quintal
0,1,2,3,4
2.32
 
6
 
 log6
 
0,1,2,3,4,5
2.58
 
7
 
 log7
 
0,1,2,3,4,5,6
2.81
 
8
 
log8
octal
0,1,2,3,4,5,6,7
3
 
9
 
 log9
 
0,1,2,3,4,5,6,7,8
3.17
 
10
 dec
lg
decimal digit or decimal unit
0,1,2,3,4,5,6,7,8,9
3.32
 Decimal logarithms have a base of 10
11
 
 
 
 
3.46
 
12
 
 
 
 
3.59
 
13
 
 
 
 
3.70
 
14
 
 
 
 
3.81
 
15
 
 
 
 
3.91
 
16
hex
log16
hexadecimal
0-9, A-F
4
http://en.wikipedia.org/wiki/Hexadecimal
20
 
 
 
0-9, A-J (or amino acids in a protein)
4.32
 
32
 
 
 
 
5
 
64
 
 
 
 
6
 
128
 
 
 
 
7
 
256
 byte
 
 byte, character
 ASCII Character
8
http://en.wikipedia.org/wiki/Byte 
8192


Chinese character
minimum Chinese character set
13

 65536
 
 
  word
 
16

232


double word
 
32

 264
 
 
  quad word
 
64

 280
 
 
 tenbyte
 
80
 
 2128
 
 
 paragraph
 
128
 
28000000
 MB
 
 megabyte
 
8x106
 
 28000000000
 GB
 
 gigabyte
 
8x109
 
 28000000000000
 TB
 
 terabyte
 
8x1012
 

Send suggestions and corrections to Shu-Kun Lin by e-mail (lin@mdpi.org) with subject title "Entropy and Information Units".
For a list of unit, see http://en.wikipedia.org/wiki/Logarithmic_unit

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Webmaster: Shu-Kun Lin; First prepared: 26 July 2004; revised: 11 December 2007