Why does a 1 TB drive show as 931 GB?

Drives are labelled in decimal: 1 TB is 1,000,000,000,000 bytes. Windows labels its figures "GB" but actually uses binary GiB of 1,073,741,824 bytes. 1 TB divided by 1 GiB is about 931, so no capacity is missing — the two sides simply use differently defined units.

When should I use GiB rather than GB?

Memory, file system blocks, and operating system capacity displays are normally binary (GiB). Drive labelling, network transfer allowances, and telecom plans are normally decimal (GB). Both are shown here so you can confirm which one a given figure means.

UNIT CONVERSION · CALCULATED FROM DEFINITIONS

GB to MB Converter

Convert data sizes with decimal GB and binary GiB kept separate.

From

1 MB = 1,000,000 bytes

FormulaMB = GB × 1,000

Ratio1 GB = 1,000 MB

Every unit in this category

bit8,000,000,000Bit

B1,000,000,000Byte

KB1,000,000Kilobyte (decimal)

MB1,000Megabyte (decimal)

TB0.001Terabyte (decimal)

KiB976,562.5Kibibyte (binary)

MiB953.6743Mebibyte (binary)

GiB0.931322575Gibibyte (binary)

TiB0.000909495Tebibyte (binary)

Common values

GB	MB
`0.5 GB`	`500 MB`
`1 GB`	`1,000 MB`
`2 GB`	`2,000 MB`
`3 GB`	`3,000 MB`
`5 GB`	`5,000 MB`
`10 GB`	`10,000 MB`
`15 GB`	`15,000 MB`
`20 GB`	`20,000 MB`
`25 GB`	`25,000 MB`
`30 GB`	`30,000 MB`
`50 GB`	`50,000 MB`
`75 GB`	`75,000 MB`
`100 GB`	`100,000 MB`
`150 GB`	`150,000 MB`
`200 GB`	`200,000 MB`
`500 GB`	`500,000 MB`
`1000 GB`	`1,000,000 MB`

About this tool

Enter GB to get MB, along with every other data unit at once. Decimal and binary are kept as separate units here: a drive manufacturer's 1 GB is 1,000,000,000 bytes, while the figure an operating system shows is usually 1 GiB = 1,073,741,824 bytes, a gap of about 7%. That is the entire reason a 1 TB drive shows up as 931 GB, and having both scales side by side makes the difference visible.

How it works

Enter a value in GB, or use any other unit as the source.
Compare the decimal (GB/MB) and binary (GiB/MiB) results.
Check the full table to see the actual byte count.

Precision and definitions

Decimal (1 GB = 1,000 MB) and binary (1 GiB = 1,024 MiB) units are provided as separate scales and never mixed.

Privacy

Every conversion runs inside this browser. The values you enter are never uploaded, stored, or written to the URL or any log.

Frequently asked questions

Why does a 1 TB drive show as 931 GB?: Drives are labelled in decimal: 1 TB is 1,000,000,000,000 bytes. Windows labels its figures "GB" but actually uses binary GiB of 1,073,741,824 bytes. 1 TB divided by 1 GiB is about 931, so no capacity is missing — the two sides simply use differently defined units.
When should I use GiB rather than GB?: Memory, file system blocks, and operating system capacity displays are normally binary (GiB). Drive labelling, network transfer allowances, and telecom plans are normally decimal (GB). Both are shown here so you can confirm which one a given figure means.

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