Convert gigabytes to kilobytes

One gigabyte is 1000000 kilobytes. To convert any amount, multiply by 1000000. Going the other way, one kilobyte is 0.000001 gigabytes.

Multiply the gigabyte figure by 1000000. So KB = GB × 1000000. For a quick mental estimate, multiplying by about 1000000 gets you within a percent or so, which is 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 kilobyte is a short email. A kilobyte is 1,000 bytes under the SI definition used by storage manufacturers and networking. Windows still labels 1,024 bytes as KB, which is the root of the 'missing space' on a new drive.

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.