Data Size Converter

What is a byte?

A byte is the fundamental unit of digital information, consisting of 8 bits. Each bit can be either 0 or 1, so one byte can represent 256 different values (2⁸). Bytes are the building blocks of all digital storage — every file on your computer, every photo, and every video is measured in bytes and multiples of bytes.

Storage capacities are expressed using metric prefixes applied to bytes: kilobytes (KB), megabytes (MB), gigabytes (GB), terabytes (TB), and beyond. However, there is an important distinction between how the computer industry and the International System of Units define these prefixes, which leads to real-world confusion.

Binary vs. SI (decimal) units

In binary measurement (used by operating systems and memory manufacturers), 1 KB equals 1,024 bytes (2¹⁰). In SI decimal measurement (used by hard drive and SSD manufacturers), 1 KB equals exactly 1,000 bytes (10³). This discrepancy is why a drive labeled "500 GB" shows approximately 465 GB in your operating system — both numbers are correct, they simply use different definitions.

To eliminate confusion, the IEC introduced dedicated binary prefixes in 1998: kibibyte (KiB = 1,024 bytes), mebibyte (MiB = 1,048,576 bytes), gibibyte (GiB), and tebibyte (TiB). While technically more precise, these terms have not gained wide adoption outside of Linux and technical documentation.

Bytes vs. bits

One byte equals 8 bits. Storage devices (hard drives, SSDs, USB drives) are measured in bytes, while network speeds are almost always quoted in bits per second. A "100 Mbps" internet connection transfers approximately 12.5 megabytes per second (100 ÷ 8 = 12.5). Always check whether a specification uses bytes (B) or bits (b) — the capitalization matters.

How to use this tool

Enter a value in any unit and all other conversions update instantly. The tool supports both binary (KiB, MiB, GiB, TiB) and SI decimal (KB, MB, GB, TB) units, plus bits and bytes. It handles large values with full precision, so you can convert anything from individual bytes to multi-petabyte storage arrays.

Common mistakes

The biggest mistake is confusing bytes and bits when comparing storage and network speeds. Downloading a 1 GB file over a 100 Mbps connection takes about 80 seconds, not 10 — because 1 GB is 8 Gb. Another common error is assuming that SI and binary units are interchangeable. A file that is 1 GiB (1,073,741,824 bytes) is about 7.4% larger than 1 GB (1,000,000,000 bytes).

Real-world reference sizes

A plain text email is roughly 2–5 KB. A high-resolution JPEG photo is 3–10 MB. A minute of MP3 audio at 320 kbps is about 2.4 MB. A Blu-ray movie is typically 25–50 GB. A modern AAA video game can exceed 100 GB. Cloud storage providers often offer 5–15 GB free, which is enough for thousands of documents but only a handful of uncompressed videos.

Frequently asked questions

Why does my hard drive show less space than advertised?

Hard drive manufacturers use SI units (1 GB = 1,000,000,000 bytes) while your operating system reports capacity in binary units (1 GiB = 1,073,741,824 bytes). The drive genuinely contains the advertised number of bytes — your OS simply uses a larger definition of "gigabyte."

How many bytes are in a terabyte?

In SI decimal, 1 TB = 1,000,000,000,000 bytes (one trillion). In binary, 1 TiB = 1,099,511,627,776 bytes. The binary terabyte is roughly 10% larger than the decimal terabyte.