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.
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.