TB ↔ TiB converter
Convert decimal terabytes to binary tebibytes (and GB to GiB) instantly — and finally understand why a 16 TB drive shows up as 14.55 TiB.
1 TiB = 1.099511627776 TB. Drive makers use decimal (TB = 10¹² bytes); operating systems and ZFS use binary (TiB = 2⁴⁰ bytes). The “missing” capacity is just this conversion.
Decimal vs binary — the “missing” capacity
Storage vendors measure in powers of ten (1 TB = 10¹² bytes) because that is how capacities are marketed. Operating systems, hypervisors and ZFS measure in powers of two (1 TiB = 2⁴⁰ bytes). The bytes are identical; only the unit changes — so a drive sold as 16 TB is correctly reported as 14.55 TiB. Nothing is lost.
This matters when you size an array: if you plan in TB but your platform reports TiB, you will over-estimate usable space by about 9%. That is why our RAID calculator and ZFS calculator always show both units side by side.
Related tools
Free, and they run in your browser — nothing you enter is sent to us or stored.
- IOPS ↔ MB/s ConverterConvert IOPS to throughput (MB/s) and GB/day at any block size.
- DWPD / TBW CalculatorConvert SSD endurance between drive-writes-per-day and total-bytes-written.
- Storage Solution FinderSet capacity, IOPS, workload and budget for a workload-matched platform recommendation.
- Storage EOSL CheckerLook up end-of-service-life dates for storage arrays and plan refreshes or third-party maintenance.
Common questions
Why does my 16 TB drive show as 14.55 TiB?
It is not missing capacity — it is a units difference. Drive makers sell in decimal terabytes (1 TB = 10¹² = 1,000,000,000,000 bytes). Operating systems and ZFS report binary tebibytes (1 TiB = 2⁴⁰ = 1,099,511,627,776 bytes). Dividing 16 × 10¹² by 2⁴⁰ gives 14.55 TiB — the same bytes, a different unit.
What is the difference between TB and TiB?
TB (terabyte) is decimal: 1 TB = 1000 GB = 10¹² bytes. TiB (tebibyte) is binary: 1 TiB = 1024 GiB = 2⁴⁰ bytes. 1 TiB ≈ 1.0995 TB, so binary units are always a slightly larger number of bytes for the same count. The same applies to GB vs GiB (1 GiB ≈ 1.074 GB).
Which unit should I plan storage in?
Buy in TB (how drives are labelled) but plan usable space in TiB if your OS, hypervisor or ZFS reports in TiB — otherwise you will over-estimate by about 9%. Our RAID and ZFS calculators show both side by side so you never mix them up.
Talk to a UK specialist
Get expert advice or a no-obligation quote — servers, storage, networking, maintenance, finance and cloud. We reply the same working day.