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Digital Storage Converter
Convert between bytes, kilobytes, megabytes, gigabytes and terabytes.
You buy a drive labelled 1 TB, plug it in, and your computer reports about 931 GB. Nothing is missing and nobody made a mistake. Two different, equally valid definitions of a kilobyte have been fighting for forty years, and your operating system and the manufacturer are each using a different one.
Two systems, one confusing name
Storage manufacturers use decimal units, where 1 kilobyte is exactly 1,000 bytes, 1 megabyte is 1,000,000 bytes, and so on — clean, base-10 numbers that match every other metric prefix in science. Operating systems, on the other hand, have historically used binary units, where 1 “kilobyte” is actually 1,024 bytes, because computers count in powers of two.
The gap compounds at every step. By the time you reach a terabyte, decimal and binary counting disagree by almost 10%: 1,000,000,000,000 bytes versus 1,099,511,627,776 bytes. That difference is exactly why a 1 TB drive, correctly labelled by the manufacturer’s decimal definition, shows up as roughly 931 GiB when Windows reports it using binary counting but still calls it GB.
Decimal (SI) vs binary (IEC) units
| Decimal unit | Bytes | Binary unit | Bytes |
|---|---|---|---|
| 1 kB | 1,000 | 1 KiB | 1,024 |
| 1 MB | 1,000,000 | 1 MiB | 1,048,576 |
| 1 GB | 1,000,000,000 | 1 GiB | 1,073,741,824 |
| 1 TB | 1,000,000,000,000 | 1 TiB | 1,099,511,627,776 |
Where the confusion actually bites
- Buying storage: the number on the box is decimal, but the number your OS reports after formatting is usually binary, so the drive will always look smaller than advertised.
- Internet speed: ISPs advertise in megabits per second (Mbps), not megabytes, and a byte is 8 bits — a 100 Mbps connection tops out around 12.5 MB per second, not 100.
- RAM: memory capacity has always been quoted in true binary units, which is part of why RAM figures never show the same shrinkage that drives do.
- The IEC introduced KiB, MiB and GiB in 1998 specifically to end this ambiguity, but the binary use of KB, MB and GB in everyday software has never fully gone away.
Converting between units here
- Enter the value and choose its current unit.
- Pick the unit you want to convert to.
- Read the result — this tool uses standard decimal (1,000-based) multiples, matching how storage is sold.
- For a binary (1,024-based) figure such as what your OS reports, expect the number to come out slightly smaller at each step up.
Digital storage questions
Why does my 1 TB hard drive show less than 1,000 GB?
Because the manufacturer used the decimal definition (1 TB = 1,000,000,000,000 bytes) while your operating system reports capacity using binary counting (1,024 bytes per KB) but still labels the result GB. Converting the same true byte count into binary units gives roughly 931, not 1,000.
What is the difference between MB and MiB?
MB (megabyte) properly means 1,000,000 bytes under the decimal SI system. MiB (mebibyte) means 1,048,576 bytes, the binary equivalent. Software that shows “MB” while actually calculating in binary is technically misusing the term, though the practice remains extremely common.
Is a kilobyte 1,000 bytes or 1,024 bytes?
Strictly, 1,000, by the same SI convention as every other metric kilo- prefix. Historically, though, computing used 1,024 because it is a power of two, and both conventions are still in active use depending on the context, which is precisely the source of the confusion.
Why do file sizes on my computer look bigger than the download page said?
The download page likely quoted a decimal figure while your file browser reports in binary units under the same label. A 100 MB (decimal) file becomes about 95.4 MiB, which a binary-counting file manager may still display simply as “95.4 MB”.
Does this converter use 1,000 or 1,024 for its calculations?
It uses the decimal, 1,000-based convention, matching how storage devices are marketed and sold. If you need the true binary figure your operating system would report, expect it to come out a little smaller at each step above kilobytes.
