OTHER · DATA SIZE CONVERTER
Data Size Converter Calculator
Convert between bytes, kilobytes, megabytes, gigabytes and more. Switch between SI (1000-based, kB/MB/GB) and IEC (1024-based, KiB/MiB/GiB) with explicit labeling.
About This Calculator
Convert data sizes between SI decimal units (kB, MB, GB = 1000-based, used by storage manufacturers) and IEC binary units (KiB, MiB, GiB = 1024-based, used by operating systems). Both bases are explicitly labeled to prevent the ~7–10% silent error that happens when they're conflated.
How It Works
Choose SI (decimal, 1000) or IEC (binary, 1024) as your unit base, then select from and to units. Switching base resets to sensible defaults. The byte (B) is the canonical base unit shared by both systems.
The Formula
SI: 1 kB = 1000 B, 1 MB = 1,000,000 B, 1 GB = 1,000,000,000 B. IEC: 1 KiB = 1024 B (2^10), 1 MiB = 1,048,576 B (2^20), 1 GiB = 1,073,741,824 B (2^30). At 1 GB scale: 1 GB = 0.931 GiB (~7% smaller than 1 GiB).
Frequently Asked Questions
- What is the difference between GB and GiB?
- 1 GB (gigabyte, SI) = 1,000,000,000 bytes. 1 GiB (gibibyte, IEC) = 1,073,741,824 bytes (2^30). A hard drive advertised as "1 TB" uses SI; your OS may report ~931 GiB — a ~7% difference due to the base mismatch.
- Which base should I use?
- Use SI (kB, MB, GB) when reading storage device specs or network speeds. Use IEC (KiB, MiB, GiB) when interpreting OS file sizes and memory. When in doubt, check which base the source uses.
- Why does my 1 TB hard drive show as ~931 GB in Windows?
- Hard drive manufacturers use SI (1 TB = 10^12 bytes). Windows historically reported file sizes using IEC (1024-based). 10^12 ÷ 2^30 ≈ 931 GiB, which Windows labeled as "GB" — compounding the confusion.