Data Powers of Ten
The following list is a collection of estimates of the quantities of
data contained by the various media. Each is rounded to be a power
of 10 times 1, 2 or 5. Most of the links are to small images.
The numbers quoted are approximate. In fact a kilobyte is 1024
bytes not 1000 bytes but this fact does not keep me awake at night.
- Bytes(8 bits)
- 0.1 bytes: A
binary decision
- 1 byte: A
single character
- 10 bytes: A
single word
- 100 bytes: A
telegram OR A
punched card
- Kilobyte (1000 bytes)
- 1 Kilobyte: A
very short story
- 2 Kilobytes: A Typewritten page
- 10 Kilobytes: An
encyclopaedic page OR A
deck of punched cards
- 50 Kilobytes: A compressed document image page
- 100 Kilobytes: A
low-resolution photograph
- 200 Kilobytes: A box of punched cards
- 500 Kilobytes: A very heavy box of punched cards
- Megabyte (1 000 000 bytes)
- 1 Megabyte: A
small novel OR A
3.5 inch floppy disk
- 2 Megabytes: A high resolution photograph
- 5 Megabytes: The
complete works of Shakespeare OR 30 seconds of
TV-quality video
- 10 Megabytes: A minute of high-fidelity sound
OR A
digital chest X-ray
- 20 Megabytes: A
box of floppy disks
- 50 Megabytes: A digital mammogram
- 100 Megabytes: 1
meter of shelved books OR A
two-volume encyclopaedic book
- 200 Megabytes: A
reel of 9-track tape OR An IBM 3480 cartridge
tape
- 500 Megabytes: A
CD-ROM OR The
hard disk of a PC
- Gigabyte (1 000 000 000 bytes)
- 1 Gigabyte: A pickup truck filled with paper
OR A
symphony in high-fidelity sound OR A movie at TV
quality
- 2 Gigabytes: 20
meters of shelved books OR A
stack of 9-track tapes
- 5 Gigabytes: An
8mm Exabyte tape
- 10 Gigabytes:
- 20 Gigabytes: A good collection of the works of Beethoven
OR 5
Exabyte tapes OR A VHS tape used for digital data
- 50 Gigabytes: A
floor of books OR Hundreds
of 9-track tapes
- 100 Gigabytes: A
floor of academic journals OR A
large ID-1 digital tape
- 200 Gigabytes: 50
Exabyte tapes
- Terabyte (1 000 000 000 000 bytes)
- 1 Terabyte: An
automated tape robot OR All the X-ray films in a
large technological hospital OR 50000 trees made into
paper and printed OR Daily rate of EOS data (1998)
- 2 Terabytes: An
academic research library OR A
cabinet full of Exabyte tapes
- 10 Terabytes: The printed collection of the US Library of
Congress
- 50 Terabytes: The contents of a large
Mass
Storage System
- Petabyte (1 000 000 000 000 000 bytes)
- 1 Petabyte: 3 years of EOS data (2001)
- 2 Petabytes: All US academic research libraries
- 20 Petabytes: Production of hard-disk drives in 1995
- 200 Petabytes: All printed material
OR
Production of digital magnetic tape in 1995
- Exabyte (1 000 000 000 000 000 000 bytes)
- 5 Exabytes: All words ever spoken by human beings.
- Zettabyte
(1 000 000 000 000 000 000 000 bytes)
- Yottabyte
(1 000 000 000 000 000 000 000 000 bytes)
Etymology of Units
- Kilo Greek khilioi =
1000
- Mega Greek megas =
great, e.g., Alexandros Megos
- Giga Latin gigas = giant
- Tera Greek teras =
monster
- Peta Greek pente = five,
fifth prefix, peNta - N = peta
- Exa Greek hex = six,
sixth prefix, Hexa - H = exa
Remember, in standard French, the initial H is silent, so they
would pronounce Hexa as Exa. It is far easier to call it Exa for
everyone's sake, right?
- Zetta almost homonymic
with Greek Zeta, but last letter of the Latin alphabet
- Yotta almost homonymic
with Greek iota, but penultimate letter of the Latin alphabet.
The first prefix is number-derived;
second, third, and fourth are based on mythology. Fifth and sixth
are supposed to be just that: fifth and sixth. But, with the
seventh, another fork has been taken. The General Conference of
Weights and Measures (CGMP, from the French; they have been
headquartered, since 1874, in Sevres on the outskirts of Paris) has
now decided to name the prefixes, starting with the seventh, with
the letters of the Latin alphabet, but starting from the end. Now,
that makes it all clear! Remember, both according to CGMP and SI,
the prefixes refer to powers of 10. Mega is 10**6, exactly
1,000,000, kilo is exactly 1000, not 1024.
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