Math & Statistics

Data Size Converter

Converts data sizes and shows the decimal and binary conventions side by side, because they are not the same.

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How to use this tool

  1. Paste your sizes, one per line, with or without a unit.
  2. Select Convert.
  3. Read the decimal column when you are talking to a vendor and the binary column when you are reading an operating system.
  4. Use the megabits column for anything involving network throughput, where capacity is quoted in bits.

What data size converter does

A kilobyte is 1,000 bytes and a kibibyte is 1,024, and the difference compounds: by the terabyte it is nearly nine per cent. That is the entire explanation for why a 1 TB disk shows as 931 GB in an operating system, and why a storage estimate can come out a full drive short if the two conventions get mixed halfway through a spreadsheet.

Both columns are always shown, so there is nothing to select and nothing to assume. Input accepts a unit — 1.5 GB, 1500 MiB, 2 TB — or a bare byte count. A megabits column is included as well, because network capacity is quoted in bits and storage in bytes, and that factor of eight is the other half of this family of mistakes.

Frequently asked questions

Because the manufacturer counted in decimal terabytes of 1,000,000,000,000 bytes and the operating system is displaying binary units of 1,024 each. Nothing is missing; the same bytes are being labelled under two conventions. Both columns are shown here so the gap is visible rather than surprising.

MB is 1,000,000 bytes and MiB is 1,048,576 — about 4.9% more. The difference grows with each step: roughly 2.4% at kB, 7.4% at GB and nearly 10% at TB. It is small enough to ignore in conversation and large enough to matter in a capacity plan.

Because network links are sold in bits per second and files are measured in bytes, and the factor of eight between them is the other half of this family of mistakes. A 100 Mb connection moves about 12.5 MB a second at best, which is the sum this column saves you doing.