Data Storage Unit Converter
Convert between bytes, kilobytes, megabytes, gigabytes, terabytes and their binary counterparts (KiB, MiB, GiB, TiB), plus bits. Everything runs in your browser.
Decimal (SI, drive labels)
- B
- 4,000,000,000,000
- KB
- 4,000,000,000
- MB
- 4,000,000
- GB
- 4,000
- TB
- 4
- PB
- 0.004
Binary (what your OS reports)
- KiB
- 3,906,250,000
- MiB
- 3,814,697.3
- GiB
- 3,725.2903
- TiB
- 3.637979
- PiB
- 0.003553
Bits (bandwidth)
- bit
- 32,000,000,000,000
- Kbit
- 32,000,000,000
- Mbit
- 32,000,000
- Gbit
- 32,000
Why a 4 TB drive shows up as 3.64 TiB
Drive makers sell capacity in decimal units: 1 TB is exactly 1,000,000,000,000 bytes. Operating systems usually report capacity in binary units: 1 TiB is 1,099,511,627,776 bytes, about 9.95% larger. So a drive labeled 4 TB holds 4 trillion bytes, which your OS shows as roughly 3.64 TiB. Nothing is missing. The two numbers just count differently.
The same gap trips people up when sizing an array. The RAID & ZFS calculator shows usable capacity in both, so the second figure is the one you will actually see in the OS. Picking the NAS itself? TrueNAS vs Unraid covers the tradeoffs.