Data Size Converter

Convert between bytes, KB, MB, GB, TB and more.

Unit & Calculator

Enter a value and select the unit (Bytes, KB, MB, GB, TB, or PB). The tool shows the equivalent in all other units. Toggle between binary (1024-based, e.g. KiB/MiB) and decimal (1000-based, e.g. KB/MB) to match how your system or specification measures data.

Uncheck for decimal (1000)

About Data Size Converter

Data sizes are expressed in bytes and larger units (KB, MB, GB, TB, PB). Two conventions exist: binary (base-1024), used by operating systems and memory, and decimal (base-1000), used in drive labels and many specs. This tool converts between Bytes, KB, MB, GB, TB, and PB in both modes so you can match what your OS shows or what a spec requires — with no signup and no server.

How to use

  1. Enter the numeric Value you want to convert.
  2. Select the From unit (e.g. Megabytes).
  3. Check or uncheck Binary (1024) depending on whether you need KiB/MiB/GiB (binary) or KB/MB/GB (decimal).
  4. Read the equivalent values in all units in the Results grid.

When to use

  • Understanding why a "1 TB" drive shows ~931 GB in Windows
  • Converting file sizes for documentation or specs
  • Estimating storage or bandwidth in consistent units
  • Checking data caps or quotas (often in GB) against actual usage

Details

Binary: 1 KiB = 1024 B, 1 MiB = 1024 KiB, 1 GiB = 1024 MiB, etc. Decimal: 1 KB = 1000 B, 1 MB = 1000 KB, 1 GB = 1000 MB, etc. The labels in the tool (KB, MB, GB) are used for both; when "Binary" is checked, the math uses 1024. When unchecked, the math uses 1000.

Frequently Asked Questions

What is the difference between binary and decimal?
Binary (base-1024): 1 KiB = 1024 B, 1 MiB = 1024 KiB, etc. Used by operating systems (Windows, macOS, Linux) and RAM. Decimal (base-1000): 1 KB = 1000 B, 1 MB = 1000 KB, etc. Often used by drive manufacturers and in networking. A "1 TB" drive may show ~931 GB in Windows because Windows uses binary (TiB) while the label uses decimal (TB).
Is this tool accurate for large values?
Yes. Conversions use standard formulas and JavaScript number precision is sufficient for values up to petabytes in everyday use. For scientific or extreme precision, consider the rounding shown in the results.
Does it run offline?
Yes. All conversion math runs in your browser. No data is sent to a server, so you can use it without an internet connection after the page has loaded.
Why do I see different sizes on my drive than on the box?
Drive makers usually label capacity in decimal (e.g. 1 TB = 1,000,000,000,000 bytes). Your OS often reports in binary (1 TiB = 1,099,511,627,776 bytes). So 1 TB (decimal) ≈ 0.91 TiB (binary), which appears as roughly 931 GB in Windows.