PB to TB Converter (Petabytes ⇄ Terabytes)

Convert between petabytes and terabytes in both decimal (SI) and binary (IEC) systems. Use it for data center planning, storage sizing and documentation checks.

Quick rule of thumb: in the decimal system used by storage vendors, 1 PB = 1000 TB. In the binary system used by many operating systems, the proper units are 1 PiB = 1024 TiB.

Decimal converter (SI) – 1 PB = 1000 TB

Recommended for vendor specs & high-level planning

This block uses the SI decimal definition: 1 PB = 1015 bytes, 1 TB = 1012 bytes.

Enter capacity in PB (e.g. total data lake size).

Equivalent capacity in TB using 1 PB = 1000 TB.

Presets:

Binary converter (IEC) – 1 PiB = 1024 TiB

Match OS-reported capacities (PiB/TiB)

This block uses IEC binary prefixes: 1 PiB = 250 bytes, 1 TiB = 240 bytes. Values are labelled explicitly as PiB and TiB to avoid confusion with PB/TB.

Binary unit often approximated as “PB” by operating systems.

Equivalent in TiB using 1 PiB = 1024 TiB.

Presets:

PB to TB quick reference

The table below uses the decimal SI definition (1 PB = 1000 TB), which is what most vendors and high-level designs expect.

Petabytes (PB) Terabytes (TB)
0.25 PB 250 TB
0.5 PB 500 TB
1 PB 1000 TB
2 PB 2000 TB
5 PB 5000 TB
10 PB 10000 TB

Understanding PB, TB, PiB and TiB

In storage engineering you will encounter two parallel systems for measuring large capacities: the decimal SI system and the binary IEC system. Both are valid, but they answer slightly different questions.

  • Decimal (SI) units: kB, MB, GB, TB, PB – each step is a factor of 1000.
  • Binary (IEC) units: KiB, MiB, GiB, TiB, PiB – each step is a factor of 1024.

Formal definitions

Decimal SI (used by vendors)

\(1~\text{PB} = 10^{15}~\text{bytes}\)

\(1~\text{TB} = 10^{12}~\text{bytes}\)

\(1~\text{PB} = 1000~\text{TB}\)

Binary IEC (used by OS)

\(1~\text{PiB} = 2^{50}~\text{bytes}\)

\(1~\text{TiB} = 2^{40}~\text{bytes}\)

\(1~\text{PiB} = 1024~\text{TiB}\)

Example: converting 2.5 PB to TB

  1. Use the decimal relation \(1~\text{PB} = 1000~\text{TB}\).
  2. Multiply: \(2.5 \times 1000 = 2500~\text{TB}\).
  3. Enter 2.5 in the PB field of the decimal converter: the TB field will show 2500 TB.

Example: rough mapping between PB and PiB

If your design document uses PB but your operating system reports PiB/TiB, you may want to compare the two. Since \(1~\text{PB} = 10^{15}\) bytes and \(1~\text{PiB} = 2^{50}\) bytes, we get approximately:

\(1~\text{PB} \approx 0.888~\text{PiB}\).

This explains why the OS often shows a slightly smaller figure than the marketing capacity printed on the label.

FAQ: PB to TB and binary prefixes

Why does my operating system show less capacity than the vendor?

Vendors usually quote decimal TB and PB, while operating systems often compute in binary TiB and PiB. As a result, a disk sold as “1 PB” (decimal) will appear as less than 1 PiB in the OS, even though nothing is “missing” physically.

Which unit system should I standardise on in documentation?

A pragmatic approach is to use decimal PB/TB for business-level documentation and capacity planning, and to explicitly mention binary PiB/TiB when referring to OS screenshots or low-level tuning notes. This calculator helps you keep both views aligned.

Is there any performance impact of using PB vs PiB?

No. These are just different ways of labelling the same underlying number of bytes. Performance depends on hardware, topology and workload, not on the unit system you choose.