Kilobyte per second to Byte per second
KBps
Bps
Conversion History
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Quick Reference Table (Kilobyte per second to Byte per second)
| Kilobyte per second (KBps) | Byte per second (Bps) |
|---|---|
| 1 | 1,000 |
| 7 | 7,000 |
| 56 | 56,000 |
| 128 | 128,000 |
| 512 | 512,000 |
| 1,000 | 1,000,000 |
About Kilobyte per second (KBps)
A kilobyte per second (kB/s or KBps) equals 8,000 bits per second and was the standard unit for measuring file download speeds in the dial-up and early broadband era. Download managers throughout the 1990s and 2000s displayed speeds in kB/s — a 56 kbps modem delivered about 7 kB/s, while early ADSL connections reached 256–512 kB/s. The unit remains useful for describing very slow links such as SMS data, GPRS connections, and low-speed serial interfaces.
A 56 kbps dial-up modem transferred files at roughly 7 kB/s. GPRS mobile data (2G) typically achieved 20–40 kB/s.
About Byte per second (Bps)
A byte per second (B/s or Bps) is the base byte-based unit of data transfer rate, equal to 8 bits per second. While ISPs advertise in bits per second, download managers, operating systems, and file transfer tools display speeds in bytes per second — a direct measure of how quickly usable file data arrives. The conversion between bits and bytes is constant: divide Mbps by 8 to get MB/s. At 1 B/s, transferring a 1 MB file would take about 11.5 days.
An old dial-up connection at 56 kbps delivered roughly 7,000 B/s (7 kB/s) of actual file data. USB 2.0 maxes out at about 60,000,000 B/s (60 MB/s).
Kilobyte per second – Frequently Asked Questions
How long did it take to download a song on dial-up at 7 kB/s?
A typical 4 MB MP3 file at 7 kB/s took about 9–10 minutes to download. Napster users in 1999 would queue up songs before bed and hope the phone line stayed connected overnight. A single disconnection meant starting over from scratch.
What is the difference between kB/s and KB/s?
Lowercase "k" with uppercase "B" (kB/s) means 1,000 bytes per second (SI decimal). Uppercase "K" with uppercase "B" (KB/s) traditionally meant 1,024 bytes per second (binary). In practice, most software uses them interchangeably, and the difference is only 2.4%.
Why do some apps still show download speeds in kB/s?
Apps display kB/s when transfer speeds are genuinely that slow — downloading over congested mobile networks, tethering in rural areas, or transferring tiny files where the connection never ramps up. It is also common in SSH/SCP transfers that display instantaneous speed during small file copies.
How fast was early ADSL compared to dial-up in kB/s?
The first consumer ADSL plans offered 256 kbps downstream, delivering about 32 kB/s — roughly 4.5× faster than a 56k modem. A 512 kbps plan gave 64 kB/s. That first jump from 7 to 32 kB/s felt revolutionary, cutting a 10-minute download to about 2 minutes.
What speed do text messages transfer at in kB/s?
An SMS is limited to 140 bytes (160 characters in GSM-7 encoding), and the signalling channel transmits it almost instantly. But if you think of SMS throughput over a sustained period, the practical rate is about 0.1–0.5 kB/s because of the overhead between messages.
Byte per second – Frequently Asked Questions
Why is a byte the fundamental unit of file storage but not of network speed?
Files are stored in bytes because CPUs address memory in byte-sized (8-bit) chunks — the smallest unit a program can read or write. Networks measure in bits because physical signals on a wire or fiber are serial: one bit at a time, clocked at a specific frequency. A 1 GHz signal produces 1 Gbps, not 1 GBps. The two worlds evolved independently and neither adopted the other's convention, leaving users to divide by 8 forever.
Is a byte always 8 bits?
In modern computing, yes — a byte is universally 8 bits. Historically, some architectures used 6, 7, or 9-bit bytes, which is why the unambiguous term "octet" exists in networking standards. But for all practical bandwidth conversions today, 1 byte = 8 bits.
Why is actual file download speed always less than the connection speed in bytes?
Network protocols add overhead — TCP headers, encryption (TLS), error correction, and packet framing all consume bandwidth without contributing to file data. A 100 Mbps connection might deliver 11 MB/s instead of the theoretical 12.5 MB/s because 10–15% goes to protocol overhead.
How many bytes per second does USB 3.0 actually transfer?
USB 3.0 has a theoretical maximum of 625 MB/s (5 Gbps ÷ 8), but real-world sustained transfers hit 300–400 MB/s due to protocol overhead and controller limitations. USB 3.2 Gen 2 doubles this to about 700–900 MB/s in practice.
What came first — the bit or the byte?
The bit came first, coined by Claude Shannon in 1948. The byte was introduced at IBM in the mid-1950s by Werner Buchholz to describe the smallest addressable group of bits in the IBM Stretch computer. Originally it could be any size; the 8-bit byte became standard with the IBM System/360 in 1964.