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Bits, Bytes and Bandwidth Reference Guide

2001-01-01 01:53 by
Tags: , ,

Quick Conversions...

For a quick reference, ue our Bits/Bytes Conversion Calculator.
For the few people that care to learn it right (or be confused to death), read on ;)

 

The Bits vs. Bytes Confusion

Let's start with some background information on prefixes, by mentioning the Metric system:

  • kilo (k)* = 10 ^ 3 = 1,000 thousand
  • mega (M) = 10 ^ 6 = 1,000,000 million
  • giga (G) = 10 ^ 9 = 1,000,000,000 billion
  • tera (T) = 10 ^ 12 = 1,000,000,000,000 trillion

* Note that according to the Metric system, the "k" or "kilo" prefix is always lowercase.
The binary forms of kilobytes and megabytes have become standard throughout the computer industry, although they are incorrect uses of the SI prefixes (in the IT field lowercase "k" is used to describe decimal kilobits, and capital "K" is used for binary kilobytes).

When used to describe Data Transfer Rate, bits/bytes are calculated as in the metric system

In data communications, a kilobit is a thousand bits, or 1,000 bits. It's commonly used for measuring the amount of data that is transferred in a second between two telecommunication points. Kilobits per second is usually shortened to kbps or Kbps**. Some sources define a kilobit to mean 1,024 bits. Although the bit is a unit of the binary number system, bits in data communications are discrete signal pulses and have historically been counted using the decimal number system. For example, 28.8 kilobits per second (kbps) is 28,800 bits per second.

  • 1 bit (b) = 0 or 1 = one binary digit
  • 1 kilobit ( kb) = 10^3 bits = 1,000 bits
  • 1 Megabit (Mb) = 10^6 bits = 1,000,000 bits
  • 1 Gigabit (Gb) = 10^9 bits = 1,000,000,000 bits

** Note:  Although technically speaking, the term kilobit should have a lowercase initial letter, most published reports capitalize it in abbreviation, resulting in "56 Kbps," or even the really confusing "56K."  That leaves you with the sometimes omitted lowercase "b" to distinguish between bits (b) and bytes (B). When used as a measurement of network data transfers, or throughput, always assume the word is bits first.

When used to describe Memory Size, or Data Storage bits/bytes are generally calculated as some exponent of 2

In Data storage, and when describing Memory size, a Kilobyte is 2^10, or 1024 bytes. Because of binary computer architecture and memory address boundaries, bytes are always some multiple or exponent of two.

  • 1 byte (B) = 8 bits (b)
  • 1 Kilobyte (K / KB) = 2^10 bytes = 1,024 bytes
  • 1 Megabyte (M / MB) = 2^20 bytes = 1,048,576 bytes
  • 1 Gigabyte (G / GB) = 2^30 bytes = 1,073,741,824 bytes
  • 1 Terabyte (T / TB) = 2^40 bytes = 1,099,511,627,776 bytes

Although data storage capacity, such as on hard drives is generally expressed in binary Megabytes (2^20), most Hard disk manufacturers, and some newer BIOSes use decimal megabytes (10^6), which is slightly different and it gets confusing...

  • 1 byte (B) = 8 bits (b)
  • 1 Kilobyte (K / KB) = 10^3 bytes = 1,000 bytes
  • 1 Megabyte (M / MB) = 10^6 bytes = 1,000,000 bytes
  • 1 Gigabyte (G / GB) = 10^9 bytes = 1,000,000,000 bytes
  • 1 Terabyte (T / TB) = 10^12 bytes = 1,000,000,000,000 bytes

 

Abbreviations Table

 

bit b 0 or 1
byte B 8 bits
kilobit kb 1000 bits
kilobyte (binary) KB 1024 bytes
kilobyte (decimal) KB 1000 bytes
Megabit Mb 1000 kilobits
Megabyte (binary) MB 1024 Kilobytes
Megabyte (decimal) MB 1000 Kilobytes
Gigabit Gb 1000 Megabits
Gigabyte (binary) GB 1024 Megabytes
Gigabyte (decimal) GB 1000 Megabytes

 

Bandwidth Reference Table 

DS0 (digital signal 0) is digital transmission rate of 64 Kbps, the bandwidth normally used for one telephone voice channel. It is the base multiple for both T (North America) and E (Europe) DS (digital signal) carriers.

The following table summarizes the set of signals and their relationship to the T-carrier and E-carrier systems

SG Bandwidth Reference Table

 DSx / Ex / Jx  Data rate  DS0 multiple Carrier
DS0(E0/J0) 64 kbps 1  
  128 kbps 2 ISDN
DS1 1.544 Mbps 23 (24) T1
E1 2.048 Mbps 30 (32) E1
DS1C / J1C 3.152 Mbps 46 (48) T1C / J1C
DS2 / J2 6.312 Mbps 92 (96) T2 / J2
E2 8.448 Mbps 120 (132) E2
J3 32.064 Mbps 480 J3
E3 34.368 Mbps 480 (537) E3
DS3 44.736 Mbps 644 (672) T3
STS1 51.84 Mbps 672 OC1
DS3C 89.472 Mbps 1288 (1344) T3C
J4 97.728 Mbps 1440 J3C
DS3X 134.208 Mbps 1932 (2016) T3X
E4 139.264 Mbps 1920 (2148) E4
STS-3 / SDH-1 155.52 Mbps 2016 OC3
DS4 274.176 Mbps 3864 (4032) T4
J5 400.352 Mbps 5760 J4
DS4E 411.264 Mbps 5796 (6048) T4E
STS-9 / SDH-3 466.56 Mbps 6048 OC9
DS4C 560.160 Mbps 7728 (8064) T4C
E5 565.148 Mbps 7680 (8592) E5 (4 E4 chnnels)
STS-12 / SDH-4 622.08 Mbps 8064 OC12
DS4X 822.528 Mbps 11592 (12096) T4X
STS-18 / SDH-6 933.12 Mbps 12096 OC18
DS5 1.120 Gbps 15456 (16128) T5
STS-24 / SDH-8 1.244 Gbps 16128 OC24
DS5X 1.400 Gbps 19320 (20160) T5X
DS5E 1.680 Gbps 23184 (24192) T5E
STS-36 / SDH-12 1.866 Gbps 24192 OC36
STS-48 / SDH-16 2.488 Gbps 32256 OC48
STS-96 / SDH-32 4.976 Gbps 64512 OC96
STS-192 / SDH-64 9.952 Gbps 129024 OC192
STS-256 13.271 Gbps 172032 OC256
STS-768 / SDH-256 39.813 Gbps 516096 OC768

Note: The following digital signal levels are not standardized and/or are not in common use:
DS3C, DS3X, DS4E, DS4C, DS4X, DS5, DS5X, DS5E, E5, J5, STS-9, STS-18, STS-24, STS-36, STS-256, STS-768.

 

  User Reviews/Comments:
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by Nitrofish - 2006-07-01 23:13
all of this info is really helpful, but what i came here looking for was, on our wireless router, it says its capable of a g connection (54Mbps), how would i go about converting that into megabytes/second?
by philip - 2006-07-02 13:59
You can use our bits/bytes conversion calculator to convert 54Mbps (megabits per second) into Megabytes per second:

http://www.speedguide.net/conversion.php

Note, however, that the 802.11g theoretical 54Mbs maximum throughput includes both directions, and all overhead... For all practical purposes, your connection will be up to about 20 Mbps (~2.2 Megabytes per second), and it will get slower at larger discances.
by ganaz30 - 2006-08-12 04:09
This is what i understand. ADSL2+ is way faster than ADSL. Many wireless modems now use ADSL2+. Every PC in one network that share the same connection over a modem will receive their bandwidth divided not on the same divide but depending on their usage of bandwidth. For slower connections it is not advisable to use wireless because of the bandwidth share and obstacles. Did I miss anything?
by anonymous - 2009-08-05 03:53
Good explanation but the Calculator needs to include bps and correctly use kbps (not Kbps).
by nightflare - 2010-10-30 13:04
This very good... though lengthy, worth reading .. thanks.. :) :)
by Mike - 2011-02-28 10:33
It would be great if you could put all this information in an iPhone app
by mike - 2012-10-05 23:23
This is a error in the storage (2n) calculator.

If I key in 1 Megabytes, it converts to 1048600 bytes - this is wrong.

1 Megabytes should be 1048576 which is 1024x1024.

Please correct this glaring error.
by Philip - 2012-10-13 15:30
It's been fixed, it was due to rounding. Thanks for pointing it out.
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