Byte per second to Terabit per second

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.

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.

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.

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.

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.

Global internet traffic peaks at roughly 1,000–1,500 Tbps (1–1.5 Pbps) as of 2026. This is growing at about 25% per year, driven by video streaming, cloud computing, and AI training data transfers. A single viral live event can spike regional traffic by tens of Tbps.

Internet traffic automatically reroutes through other cables and paths via BGP routing protocols, usually within seconds. Speed may degrade in the affected region but rarely drops entirely. Cable cuts happen more often than people think — about 100 per year globally, mostly from ship anchors and fishing trawlers.

Dense wavelength-division multiplexing (DWDM) sends dozens of different light colors (wavelengths) through a single fiber simultaneously, each carrying its own data stream. A modern cable contains multiple fiber pairs, each carrying 100+ wavelengths, with each wavelength modulated at 400 Gbps or more.

Netflix's library is estimated at around 30–40 petabytes. At 1 Tbps, downloading the entire catalog would take roughly 70–90 hours. At 100 Tbps (a realistic submarine cable capacity), you could theoretically grab all of Netflix in under an hour.

Researchers at Japan's NICT achieved 22.9 Pbps (22,900 Tbps) through a single multicore fiber in 2024. That is enough to transfer the entire Library of Congress in a fraction of a second. These lab records typically reach commercial deployment 5–10 years later.