Bit to Exabyte

A bit is a single binary value (0 or 1); a byte is a group of 8 bits. Bytes are the standard unit for file sizes, memory, and storage. Network speeds are typically quoted in bits per second (Mbps), while file sizes use bytes (MB) — so a 100 Mbps connection downloads 100 megabits, or about 12.5 megabytes, per second.

Networking hardware physically transmits one bit at a time over a wire or radio signal, so bits per second is the natural unit for measuring throughput. The convention predates widespread file-size awareness. When you see "100 Mbps broadband", your actual download speed in MB/s is about 1/8 of that — roughly 12.5 MB/s.

A classical bit is definitively 0 or 1. A qubit can exist in a superposition of both states simultaneously, described by two complex probability amplitudes. When measured, a qubit collapses to 0 or 1 — yielding one classical bit of information. The power of qubits lies in entanglement and interference during computation, not in storing more data per unit. A 100-qubit quantum computer does not store 100 bits more efficiently; it explores 2¹⁰⁰ computational paths in parallel for specific algorithm types like factoring and search.

Information theory, developed by Claude Shannon in 1948, quantifies how much information a message contains. One bit is the amount of information needed to resolve a choice between two equally likely outcomes. This abstraction underpins all digital compression, encryption, and error-correction — from MP3 audio to HTTPS security.

In practice, modern computers cannot address or store a single bit individually — the minimum addressable unit is one byte (8 bits). Trying to store a single bit requires a full byte, with 7 bits unused. Some specialised hardware and bit-packing algorithms can store multiple boolean values per byte, but standard memory hardware works at byte granularity.

One exabyte = 1,000,000 terabytes = 1,000 petabytes. If you filled 1 TB external hard drives and stacked them end to end, 1 EB worth would stretch roughly 200 km. In content terms: 1 EB can store about 250,000 years of HD video, or about 100 billion hours of music at 128 kbps. All the data produced by the Large Hadron Collider per year is about 15 petabytes — still 67× less than one exabyte.

Global data creation, capture, copy, and consumption is estimated at roughly 2.5 exabytes per day (IDC 2023 estimate), growing roughly 23% annually. This includes IoT sensor readings, financial transactions, social media posts, surveillance camera footage, scientific instrument output, and all other digital activity. Most of this data is transient and never stored long-term.

Amazon Web Services, Microsoft Azure, and Google Cloud each store estimated tens to hundreds of exabytes of customer data in their cloud platforms. Meta (Facebook/Instagram) stores an estimated 100+ exabytes across all data types. The NSA's Utah Data Center is estimated to hold yottabytes in capability, though actual stored volumes are classified. Collectively, global cloud storage is in the hundreds-of-exabytes range.

An exabyte (EB) = 10¹⁸ bytes (SI decimal). An exbibyte (EiB) = 2⁶⁰ bytes = 1,152,921,504,606,846,976 bytes — about 15.3% larger. This is the largest practically relevant gap between SI and IEC units in storage contexts. For a data center procuring 10 EB of storage, the SI vs IEC difference represents about 1.5 EB of capacity discrepancy in the contract.

Data archaeology is the practice of recovering information from obsolete storage media and formats — 9-track magnetic tapes, 8-inch floppy disks, MiniDiscs, Zip drives, and early optical formats. The challenge is threefold: hardware to read the media no longer exists or is failing, file formats and encoding schemes are undocumented, and magnetic media degrade over time (tape has a 10–30 year shelf life). At exabyte scale, organisations like national archives face the prospect of vast digital collections becoming unreadable within decades. Active migration strategies — periodically copying data to current formats and media — are the only reliable defense, but the cost scales linearly with data volume.