Kilobit per second
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| Bit rates | ||
|---|---|---|
| Decimal prefixes (SI) | ||
| Name | Symbol | Multiple |
| kilobit per second | kbit/s | 103 |
| megabit per second | Mbit/s | 106 |
| gigabit per second | Gbit/s | 109 |
| terabit per second | Tbit/s | 1012 |
| Binary prefixes (IEC 60027-2) |
||
| kibibit per second | Kibit/s | 210 |
| mebibit per second | Mibit/s | 220 |
| gibibit per second | Gibit/s | 230 |
| tebibit per second | Tibit/s | 240 |
A kilobit per second (kbit/s or kbps or kBaud) is a unit of data transfer rate equal to 1,000 bits per second. It is sometimes mistakenly thought to mean 1,024 bits per second, using the binary meaning of the kilo- prefix, though this is incorrect.
[edit] Examples
- 56K modem — 56,000 bit/s
- 128 kbit/s mp3 — 128,000 bit/s [1]
- 64k ISDN — 64,000 bit/s [2]
- 1536k T1 — 1,536,000 bit/s (1.536 Mbit/s)
Most digital representations of audio are measured in kbit/s:
(These values vary depending on audio data compression schemes)
- 4 kbit/s – minimum necessary for recognizable speech (using special-purpose speech codecs)
- 8 kbit/s – telephone quality
- 32 kbit/s – MW quality
- 96 kbit/s – FM quality
- 192 kbit/s – Nearly CD quality for a file compressed in the MP3 format
- 1,411 kbit/s – CD audio (at 16-bits for each channel and 44.1 kHz)
[edit] Related units
Another unit of data transmission is the kilobyte per second (kbyte/s or kB/s or kBps), which is 1,000 or 1,024 bytes per second. Bytes are typically 8 bits in modern systems, but even when 8-bit bytes are used, the number of kbyte/s is not necessarily exactly one eighth the number of kbit/s because the count of bytes might not include framing bits. For example, a 56 kbit/s RS-232 serial line transfers only 5.6 kbyte/s — not 7 kbyte/s — when used in the most common configuration (asynchronous, 8 data bits, no parity, one stop bit). It is fairly common to use kbyte/s with the binary meaning (1,024 byte/s) — more so than for kbit/s — perhaps because of the close relationship with the common binary usage of kilobyte for measuring file sizes.
Another related unit is the kibibit per second:
- 104 = 1,000 bit/s = 1 kbit/s (one kilobit or one thousand bits per second)
- 210 = 1,024 bit/s = 1 Kibit/s (one kibibit per second)
