File Size Converter

A file size converter changes data amounts between units such as bytes, megabytes and gigabytes. There are two standards: decimal SI units, where 1 KB = 1,000 bytes, and binary IEC units, where 1 KiB = 1,024 bytes. This tool supports both, plus bits and megabits, and labels which standard each unit uses.

Free, no signup. Runs entirely in your browser; files and text are not uploaded.

How to use the File Size Converter

  1. Enter the size in the Value box.
  2. Choose the unit you have in From, such as GB (decimal) or GiB (binary).
  3. Choose the unit you want in To.
  4. Read or copy the result and compare every unit in the table.

Features

  • Decimal SI units: KB, MB, GB, TB, PB (powers of 1,000)
  • Binary IEC units: KiB, MiB, GiB, TiB, PiB (powers of 1,024)
  • Bits, megabits and gigabits for network speeds
  • Presets such as 1 TB drive → GiB and Mb → MB
  • All-units table, precision control and copy buttons

Frequently asked questions

Is 1 GB 1,000 MB or 1,024 MB?

In the decimal SI standard, 1 GB = 1,000 MB. In the binary standard, 1 GiB = 1,024 MiB. Windows uses binary values but labels them GB, which causes the confusion.

Why does my 1 TB drive show about 931 GB?

Drive makers sell 1 TB as 1,000,000,000,000 bytes. Windows divides by 1,024³ and shows about 931 "GB", which is really 931 GiB.

What is the difference between Mb and MB?

Mb (megabit) is used for network speeds; MB (megabyte) is used for file sizes. One byte is 8 bits, so 100 Mb is 12.5 MB.

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Built and reviewed by Naqash Thaheem, Technical Project Manager. Last reviewed 2026-09-24.