Convert gigabytes to terabytes

One gigabyte is 0.001 terabytes. To convert any amount, multiply by 0.001. Going the other way, one terabyte is 1000 gigabytes.

Multiply the gigabyte figure by 0.001. So TB = GB × 0.001. For a quick mental estimate, dividing by about 1000 gets you close enough for most everyday purposes.

One gigabyte is about two hours of HD video. A gigabyte is one billion bytes. A drive sold as 1 TB holds 1,000 GB decimal, which your operating system may display as 931 GiB — nothing is missing, the units differ.

One terabyte is a large photo and video library. A terabyte is a trillion bytes. Consumer drives are sold in decimal terabytes, which is why a '2 TB' drive shows as roughly 1.82 TiB once formatted.

Because two different definitions are in play. Storage manufacturers use decimal units — 1 TB means exactly one trillion bytes. Windows and many other systems display binary units but label them with decimal names, so they show that same drive as 931 "GB" when they mean 931 gibibytes. Nothing is missing and nothing is faulty; the drive holds exactly what it says, measured differently. The IEC standardised kibi, mebi and gibi in 1998 specifically to end this, but adoption has been patchy.

Yes — both decimal and binary prefixes are exactly defined powers, so every figure here is exact rather than approximate. The results are shown to seven significant figures; the underlying arithmetic uses full double precision.