What is this converter?
Converts data sizes between bits, bytes, decimal units (kilobyte to terabyte, powers of 1,000) and binary units (kibibyte to tebibyte, powers of 1,024). Both families are offered because storage and software genuinely use different ones.
Use it when:
- A drive advertised as 1 TB shows less capacity in your operating system and you want to know why.
- You are converting a file size between the units a tool reports and the units you think in.
- You need to be explicit about whether a "GB" means 1,000³ or 1,024³ bytes.
Intended for: Developers, system administrators, and anyone reconciling reported storage sizes.
How is this calculated?
- Each supported unit is defined by a fixed conversion factor relative to one base unit for the quantity (for example, the metre for length).
- The value you enter is first converted from the source unit into that base unit by multiplying by the source unit's factor.
- The base value is then converted into the target unit by dividing by the target unit's factor.
- Because both factors are exact constants, the conversion is a single deterministic multiplication and division — the same input always produces the same output.
Formulas
Decimal units
1 KB = 1,000 bytes; 1 MB = 1,000² bytes; 1 GB = 1,000³ bytes
The SI-prefixed family, used by drive manufacturers and network speeds.
Binary units
1 KiB = 1,024 bytes; 1 MiB = 1,024² bytes; 1 GiB = 1,024³ bytes
The IEC binary family, used by most operating systems when reporting memory and file sizes.
Example
A drive advertised as 1 TB, shown by an operating system in binary units.
- 1 TB (decimal) is 1,000,000,000,000 bytes.
- 1 TiB (binary) is 1,099,511,627,776 bytes.
- 1,000,000,000,000 ÷ 1,099,511,627,776 ≈ 0.9095.
Result: A 1 TB drive shows as about 0.91 TiB — roughly 9% less, which is a units difference, not missing capacity.
Frequently asked questions
Why does my 1 TB drive show as about 931 GB?
The manufacturer used decimal terabytes (1,000⁴ bytes) and your operating system displays binary gibibytes (1,024³ bytes) while labelling them "GB". No capacity is missing — the two are just counting in different bases.
What is the difference between a bit and a byte?
A byte is 8 bits. Network speeds are usually quoted in bits per second and file sizes in bytes, so a 100 Mbps connection transfers at most about 12.5 MB per second.
Which family should I use?
Use decimal units for storage capacity and network speeds, and binary units for memory and most operating-system file-size reporting. When it matters, write KiB/MiB/GiB explicitly — that is exactly why the IEC prefixes exist.
Assumptions
What this converter takes as given:
- Conversion factors are the internationally standardised definitions of each unit, not regional or historical variants.
- The value you enter is treated as an exact quantity — no measurement uncertainty is carried through the conversion.
- Results are rounded only for display; the underlying arithmetic uses full precision.
Limitations
What this converter cannot know or does not model:
- The converter does not know the precision of your original measurement, so it cannot report significant figures for you.
- Units that share a name but differ by region or era (for example, different definitions of a gallon or a ton) are offered only in the variants listed in the unit menu.
- Very large or very small magnitudes are subject to the limits of double-precision floating-point arithmetic.
References
- IEC 80000-13 — binary prefixes for units of information — IEC. The standard that defines kibi-, mebi-, and gibi- to remove the decimal/binary ambiguity.