Why is 1 KB sometimes 1000 bytes and other times 1024? The answer lies in computing history.
A bit is the smallest unit of information in computing: a single binary digit that can be 0 or 1. A byte is a group of 8 bits, and is the practical unit used to represent a simple text character (such as a letter). From the byte arise the familiar multiples: kilobyte (KB), megabyte (MB), gigabyte (GB), and terabyte (TB). Understanding the relationship between these units is essential to correctly interpret storage capacities and network speeds.
Historically, computing used powers of 2 to define these multiples, because computers operate internally in binary. Thus, 1 kilobyte was commonly treated as 1,024 bytes (2¹⁰), 1 megabyte as 1,048,576 bytes (2²⁰), and 1 gigabyte as 1,073,741,824 bytes (2³⁰). This convention arose naturally from the binary architecture of computers and was the informal standard for decades, although it technically conflicted with the prefix "kilo," which in the International System means 1,000.
The hard drive and storage industry, however, started using the decimal standard — in which 1 kilobyte = 1,000 bytes, 1 megabyte = 1,000,000 bytes, and 1 gigabyte = 1,000,000,000 bytes — aligning with the universal metric use of prefixes. This created a persistent divergence: the same term "gigabyte" came to have two different values depending on who used it, generating confusion among manufacturers, operating systems, and users.
To resolve this ambiguity, the International Electrotechnical Commission (IEC) standardized binary prefixes in 1998: kibibyte (KiB = 1,024 bytes), mebibyte (MiB = 1,048,576 bytes), and gibibyte (GiB = 1,073,741,824 bytes), reserving the terms kilobyte, megabyte, and gigabyte exclusively for decimal values (1,000, 1,000,000, 1,000,000,000). TudoConversor makes this distinction clear, offering both decimal units (KB, MB, GB) and binary units (KiB, MiB, GiB).
The most visible practical consequence of this difference: a flash drive sold as "64 GB" (64,000,000,000 bytes in the manufacturer's decimal standard) shows up in Windows as approximately 59.6 GB, because Windows historically displays space using the binary standard (gibibytes) but labels it as "GB." There is no defect or loss of space — it is the same number of bytes displayed under two different measurement rulers. macOS and most Linux distributions have already adopted the decimal standard for display, showing a value closer to the advertised one.
Another frequent confusion involves network speeds, which are measured in bits per second (bps, Kbps, Mbps), while file sizes are measured in bytes (KB, MB, GB). Since 1 byte = 8 bits, a "100 Mbps" connection transfers data at about 12.5 MB/s — not 100 MB/s, as many assume. This distinction is exploited even in internet marketing, where the number in megabits looks larger and more attractive than the equivalent in megabytes.
For this reason, when comparing storage capacities or transfer speeds, always check whether the values are in decimal or binary units, and whether they are in bits or bytes. The TudoConversor data storage converter applies the correct factors with double precision, covering bit, byte, kilobyte, kibibyte, and all multiples up to terabytes and tebibytes, ensuring reliable conversions between the decimal and binary standards.
The fundamental unit of digital information is the bit, which can take only two values, 0 or 1, reflecting the on/off state of an electronic circuit. The byte, composed of 8 bits, emerged as a practical unit because 8 bits allow representing 256 distinct values — enough space to encode all characters of an extended alphabet, such as ASCII. This historical choice of 8 bits per byte consolidated in the 1960s and became the universal standard, although technically the size of a byte could vary in early systems — today, a byte is always 8 bits by convention.
The confusion between bits and bytes directly affects the perception of internet speed. A "100 megabits per second" plan (100 Mbps) corresponds to about 12.5 megabytes per second (MB/s) in actual file transfer, since 1 byte = 8 bits. Downloading a 1 gigabyte file at 100 Mbps takes approximately 80 seconds, not 10 seconds as someone might assume by confusing megabits with megabytes. This distinction is the most common source of complaints about undelivered internet speed, when in fact the unit was simply misunderstood.