Bits, Bytes and Bandwidth Reference Guide

Bits, Bytes and Bandwidth Reference Guide 2001.01.01 01:53 EST by Philip 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.

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