Data Transfer Rate Converter

About data transfer rate units

Data transfer rate measures how quickly digital information moves from one place to another — bits or bytes per second. The base SI unit is the bit per second (bps), and internet speeds are almost universally advertised in megabits per second (Mbps) or gigabits per second (Gbps). File sizes, on the other hand, are quoted in megabytes (MB) or gigabytes (GB). Because 1 byte = 8 bits, a 100 Mbps broadband connection downloads at only about 12.5 MB/s — so a 1 GB file takes roughly 80 seconds, not 10. This factor-of-8 gap between advertised speed and felt download speed is the single most common source of confusion for home users.

History & origin

The bit-per-second unit emerged alongside early telecommunications. Baud — named after French engineer Émile Baudot — originally described symbol rate in telegraph systems and is still sometimes confused with bit rate, but they are equal only in systems where each symbol encodes exactly one bit. As digital networking grew in the 1980s and 1990s, the kilobit-per-second and megabit-per-second became standard ISP advertising units because they produce larger, more impressive-sounding numbers than their byte-per-second equivalents.

Tips

Case matters critically for data-rate units: a lowercase 'b' means bits, an uppercase 'B' means bytes. Mbps = megabits per second; MB/s = megabytes per second. These differ by a factor of 8. An ISP advertising '1 Gbps' fibre delivers up to 125 MB/s of actual file throughput under perfect conditions — and real-world overhead from TCP/IP headers, protocol handshakes, and network congestion typically reduces that to 90–110 MB/s. Always convert the advertised Mbps figure to MB/s before estimating download times.

Common questions

Why does my 100 Mbps connection only download files at about 12 MB/s?

Because internet speeds are measured in megabits (Mb) while file sizes are measured in megabytes (MB), and 1 byte = 8 bits. 100 Mbps ÷ 8 = 12.5 MB/s maximum throughput. Actual speeds are usually a bit lower due to protocol overhead and network conditions.

What is the difference between Mbps and MB/s?

Mbps is megabits per second; MB/s is megabytes per second. Since 1 byte = 8 bits, the conversion is simply: MB/s = Mbps ÷ 8, or Mbps = MB/s × 8. ISPs use Mbps; download managers typically show MB/s.