A kilobit per second (kbit/s or kbps) is a unit of data transfer rate equal to 1,000 bits per second. It is sometimes used to mean 1,024 bits per second, using the binary meaning of the kilo- prefix, though this is rare and non-standard.

Examples:

• 56K modem — 56,000 bit/s
• 128 kbit/s mp3 — 128,000 bit/s ^*
• 64k ISDN — 64,000 bit/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 – "CD quality" for an mp3
• 1,411 kbit/s – CD audio (at 16-bits and 44.1 kHz)

Related units

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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:

10³ = 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)

See also

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• kilobit/kibibit
• kilobyte/kibibyte
• Binary prefix

Telecommunications terms | Units of flow

Kilobits por segundo | Kilobit par seconde | Kbps | Kilobit per secondo | Kilobit por segundo | Килобит в секунду | Kilobit per second