Terabits to Gigabytes (Tb to GB)

1 terabit equals 125 gigabytes exactly.

1 terabit = 125 gigabytes

How to convert terabits to gigabytes

To convert terabits to gigabytes, multiply the number of terabits by 125. This factor is exact. To go the other way, multiply gigabytes by 0.008.

gigabytes = terabits × 125

Example: 10 terabits = 1,250 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

Terabit (Tb)

ComputingCurrent unit

10¹² bits (125 GB).

Network engineers reach for the terabit because link speeds are quoted in bits per second, and Wikipedia's article on the bit confirms that transfer rates conventionally use decimal SI multiples. One terabit is exactly 10^12 bits, which at eight bits per byte is 125,000,000,000 bytes, or 125 gigabytes. Tera, adopted into the SI in 1960, is the first prefix after giga.

The commonly used symbol is Tbit, and the IEEE 1541 standard recommends lowercase b, giving Tb. That shorthand is risky because capital B means byte, a factor of eight apart. In the IEC naming, a terabit is a decimal unit; its binary counterpart, the tebibit, is 2^40 bits, about 10 percent larger.

Because it is quoted in bits, the terabit suits data rates, where terabits per second describe very high-capacity links, and it is eight times smaller than the terabyte.

1 terabit = 125,000,000,000 bytes (exactly).

Sources: Wikipedia: Bit; Wikipedia: Metric prefix; Wikipedia: Binary prefix

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.