Terabytes to Gigabytes (TB to GB)

1 terabyte equals 1,000 gigabytes exactly.

1 terabyte = 1,000 gigabytes

How to convert terabytes to gigabytes

To convert terabytes to gigabytes, multiply the number of terabytes by 1,000. This factor is exact. To go the other way, multiply gigabytes by 0.001.

gigabytes = terabytes × 1,000

Example: 10 terabytes = 10,000 gigabytes.

Decimal prefixes (kB, MB, GB) are powers of 1,000; binary prefixes (KiB, MiB, GiB) are powers of 1,024. Storage makers use decimal; Windows reports binary but labels it GB.

About these units

Terabyte (TB)

ComputingCurrent unit

1,000 gigabytes (10¹² bytes), the capacity of a typical modern hard drive.

Tera comes from the SI prefix for 10 to the twelfth, so a terabyte is one million million bytes. Computer memory is binary, so the prefixes were once used for powers of two, which caused confusion. IUPAC proposed binary prefixes such as kibi, mebi and gibi in 1995, and the IEC adopted them in December 1998 and published the standard in January 1999. The tebibyte is the binary counterpart, about 9 percent larger than the terabyte.

Hitachi introduced the first one-terabyte consumer hard drive in 2007. For scale, one terabyte is about 20 standard Blu-ray discs or 213 DVDs. The mismatch shows at this size: a drive sold as 1 TB may be reported as about 931 GB, because Windows uses the historic binary convention. macOS and iOS did the same until Mac OS X 10.5 Leopard and iOS 10, then switched to powers of 10.

1 terabyte = 1,000,000,000,000 bytes (exactly).

Sources: Wikipedia: Terabyte; Wikipedia: Binary prefix; NIST: Prefixes for binary multiples

Gigabyte (GB)

ComputingCurrent unit

1,000,000,000 bytes (decimal). Storage manufacturers and phone makers use this definition.

The gigabyte is where the decimal-versus-binary dispute turned into lawsuits. Drive makers advertise capacity in decimal units, so a 500 GB drive holds 500 billion bytes, but Windows reports sizes in binary units and shows about 465.7 of what it labels GB for the same drive. Early challenges against Western Digital and Seagate were settled, with Western Digital adding disclaimers that usable capacity may differ from the advertised figure.

A 2019 lawsuit was decided in the manufacturers' favor, with the court relying on the decimal definition. For scale, one gigabyte holds roughly an hour of standard-definition video at 2.2 Mbit/s. A single-layer DVD+R holds about 4.7 GB and a single-layer Blu-ray about 25 GB. RAM is still often sized in binary gigabytes, which the IEC would call gibibytes.

1 gigabyte = 1,000,000,000 bytes (exactly).

Sources: Wikipedia: Gigabyte; Wikipedia: Binary prefix; Wikipedia: Gibibyte

Related conversions

See all digital storage units.