Data Converter
Enter a value and its unit and convert it to every other: bits, bytes and the decimal (SI, base 1000) and binary (IEC, base 1024) multiples. 1 Byte = 8 bits. Nothing is sent to any server.
Decimal · SI (base 1000)
| Unit | Value | In bytes |
|---|
Binary · IEC (base 1024)
| Unit | Value | In bytes |
|---|
SI vs IEC · why a 1 TB disk is 0.909 TiB
1. There are two families of
prefixes. The decimal ones (SI) are powers of
1000: kB=10³ B, MB=10⁶,
GB=10⁹, TB=10¹². The binary ones (IEC)
are powers of 1024: KiB=2¹⁰ B,
MiB=2²⁰, GiB=2³⁰, TiB=2⁴⁰.
2. The IEC 60027-2 standard
created the Ki/Mi/Gi/Ti prefixes (kibi, mebi, gibi, tebi)
precisely to remove the ambiguity: a kB is 1000 bytes, a
KiB is 1024 bytes.
3. Disk manufacturers use the
decimal system: 1 TB = 1,000,000,000,000 bytes. The
operating system usually measures in binary, so it divides
by 1024⁴:
1·10¹² / 2⁴⁰ ≈ 0.909 TiB. That is why the disk "looks" smaller.
4. The difference grows with scale: ~2.3 % at kilo, ~4.6 % at mega, ~6.9 % at giga and ~9.1 % at tera. No space is missing: only the unit it is measured in changes.
5. Network speeds are in
bits (Mbps), not bytes. 1 Byte = 8 bits, so
divide by 8 to go from bits to bytes.
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How it works
The converter takes a value with its unit (bit, byte or any multiple) and expresses it in all the others: bits, bytes, the decimal SI multiples in base 1000 (kB, MB, GB, TB, PB) and the binary IEC 60027-2 multiples in base 1024 (KiB, MiB, GiB, TiB, PiB). It works with bytes as the internal unit and the fixed rule 1 byte = 8 bits.
The conversion is pure arithmetic: the value is multiplied by its unit factor to bring it to bytes (for example GB = 10^9 B, GiB = 2^30 B) and then divided by the factor of each target unit. The two tables, decimal and binary, show the same figure side by side, which is exactly where the confusion between what a disk box promises and what the operating system reports comes from.
Example: why does a 1 TB disk show about 931 GiB?
- The manufacturer uses the decimal system:
1 TB = 10^12 = 1,000,000,000,000 bytes. - The operating system measures in binary: divide by
2^30for GiB:10^12 / 1,073,741,824 ≈ 931.3 GiB(or by2^40: 0.909 TiB). - No space is missing: they are the same bytes measured with two different units, with a 9.1 % gap at the tera scale.