Is a kilobyte 1,000 or 1,024 bytes?

Both, depending on who is speaking. Storage manufacturers use the decimal SI meaning, 1,000 bytes, and operating systems have historically used 1,024. The IEC names kibibyte, mebibyte and gibibyte exist to say 1,024 unambiguously, and this converter offers both so the difference is visible rather than assumed.

Why does my 1 TB drive show as 931 GB?

The drive holds 1,000,000,000,000 bytes as the manufacturer counts them, and the operating system divides by 1,024 three times, giving 931 GiB while labelling it GB. Nothing is missing; the two are counting in different bases.

Technologydata

Data Unit Converter

Data sizes with base-2 and base-10 units kept properly distinct. A "gigabyte" on a disk label and a "GB" in your operating system are not the same number, and the 7% gap is why a 1 TB drive shows as 931 GB.

Also called: gb to gib, mb to mib, bytes converter.

Result

0.931323

1 Gigabyte (10⁹) is 0.931323 Gibibyte (2³⁰). The factor is 0.9313225746, and the inverse is 1.073741824. The table below gives the same value in every data unit at once.

Conversion factor

0.9313225746

Inverse factor

1.073741824

Value in byte

1,000,000,000.0000002384

Converting from

Gigabyte (10⁹)

Converting to

Gibibyte (2³⁰)

Dimension

data

How this is calculated

The same value in every data unit

Unit	Value
Bit	8,000,000,000
Byte	1,000,000,000
Kilobyte (10³)	1,000,000
Megabyte (10⁶)	1,000
Gigabyte (10⁹)	1
Terabyte (10¹²)	0
Kibibyte (2¹⁰)	976,562.5
Mebibyte (2²⁰)	953.67

Method and background

How this is calculated

Storage vendors use powers of ten (1 GB = 10⁹ bytes) and operating systems traditionally use powers of two (1 GiB = 2³⁰ bytes). The IEC binary prefixes (kibi, mebi, gibi) exist to name the difference, and the gap compounds: 7% at giga, 10% at tera.

result = value * factor_from / factor_to

k: Each unit's size in byte

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

1 GB is 0.931 GiB

Value: 1
From: Gigabyte (10⁹)
To: Gibibyte (2³⁰)

Result0.931323

10^9 / 2^30

Open this example

a byte is 8 bits

Value: 1
From: Byte
To: Bit

Result8

definition

Open this example

identity

Value: 512
From: Megabyte (10⁶)
To: Megabyte (10⁶)

Result512

degenerate case

Open this example

Written about this

Your 1 TB drive is not missing 69 GB · 1 min · A new 1 TB drive reports 931 GB and nothing is wrong. The manufacturer and the operating system are counting in different bases, and both are telling the truth.

Frequently asked questions

Is a kilobyte 1,000 or 1,024 bytes?: Both, depending on who is speaking. Storage manufacturers use the decimal SI meaning, 1,000 bytes, and operating systems have historically used 1,024. The IEC names kibibyte, mebibyte and gibibyte exist to say 1,024 unambiguously, and this converter offers both so the difference is visible rather than assumed.
Why does my 1 TB drive show as 931 GB?: The drive holds 1,000,000,000,000 bytes as the manufacturer counts them, and the operating system divides by 1,024 three times, giving 931 GiB while labelling it GB. Nothing is missing; the two are counting in different bases.