GB to TB Converter

Using the decimal definition, 1 TB = 1,000 GB:

terabytes = gigabytes ÷ 1000

Why your 1 TB drive shows 931 GB. This is the most-asked question about digital storage, and nothing is wrong with the drive.

A manufacturer sells 1 TB as 1,000,000,000,000 bytes — the SI meaning of "tera", and what the box says. Windows then divides by 1,024 three times:

1,000,000,000,000 ÷ 1,024 ÷ 1,024 ÷ 1,024 = 931.32

and displays "931 GB". The correct label for that figure is 931 GiB (gibibytes), but Windows writes GB. Same bytes, two conventions, one confusing number. macOS and Linux report 1,000 GB and agree with the box.

Expected capacities:

Sold as	Actual bytes	Windows shows
500 GB	500,000,000,000	465 GB
1 TB	1,000,000,000,000	931 GB
2 TB	2,000,000,000,000	1.82 TB
4 TB	4,000,000,000,000	3.64 TB

Formatting takes a further slice for the file system — typically under 1% on NTFS, more on older systems.

A class action against several drive makers over this labelling was settled in 2007; the outcome was a footnote on the box, not a change in the definition.

For anything you are budgeting — backups, media libraries, RAID capacity — plan with the Windows figure, since that is the space you can actually fill.