RunTheTests

Data Size Converter

Convert between bytes, KB, MB, GB and TB — decimal and binary, side by side.

System verdict

RESULT

1 TB = 1,000,000,000,000 bytes

Decimal units (KB, MB, GB) use powers of 1000 and are how storage is sold; binary units (KiB, MiB, GiB) use powers of 1024 and are how your operating system reports free space. A "1 TB" drive is 1000 GB decimal, which the OS shows as about 931 GiB — same drive, different unit.

Diagnostic telemetry
Bytes
1,000,000,000,000
Decimal (÷1000)How storage is sold
1 TB
Binary (÷1024)How your OS reports it
931.323 GiB
KB / KiB
1,000,000,000 / 976,562,500
MB / MiB
1,000,000 / 953,674.316
GB / GiB
1,000 / 931.323
TB / TiB
1 / 0.9095

What this cannot tell you

  • Pure arithmetic. It converts between units; it does not measure any actual disk or file.
  • Decimal (KB/MB/GB) and binary (KiB/MiB/GiB) are genuinely different units. The tool shows both because manufacturers and operating systems disagree about which to call "GB".

How this calculation works

Enter a value and its unit; the tool converts to bytes and then to every common unit, in both the decimal and binary systems. Decimal units step by 1000, binary units by 1024, so the two ladders diverge more the larger the number gets.

What the results mean

Decimal (÷1000)
KB, MB, GB, TB. Powers of 1000. How storage and bandwidth are sold and advertised.
Binary (÷1024)
KiB, MiB, GiB, TiB. Powers of 1024. How operating systems report memory and free space.
The drive-size gap
A "1 TB" drive is 1,000,000,000,000 bytes (decimal), which is about 931 GiB in binary — the number your OS shows. Nothing is missing; it is the same size in a different unit.

Frequently asked questions

Why does my 1 TB drive show as 931 GB?

Because the manufacturer measured in decimal (1 TB = 1,000,000,000,000 bytes) and your operating system reports in binary (1 GiB = 1,073,741,824 bytes), while still labelling it "GB". Divide the decimal bytes by 1024³ and you get ~931. The drive holds exactly what was advertised; the two are just using different units with the same name.

Which is correct, GB or GiB?

Both — they are different units. Strictly, GB should mean 1000³ bytes and GiB 1024³, and that is what this tool follows. In practice operating systems say "GB" when they mean GiB, which is the entire source of the confusion.

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