Gigabyte to Terabyte
Convert gigabyte (GB) to terabyte (TB) instantly. Understand file sizes and storage plans.
Gigabyte → Terabyte
0.000977
TB
1 GB = 0.000977 TB
Frequently asked questions
Because the manufacturer and the operating system use different definitions of the prefix. The manufacturer sells 1 TB decimal, which is 1,000,000,000,000 bytes. Windows divides that by 1,024 three times and labels the result GB, though it is really GiB, giving 931.3. Nothing has been lost and no one is cheating — the gap is 9.95% at terabyte scale.
About 250 hours of 1080p at roughly 4 GB per hour, or around 50 hours of 4K footage at roughly 20 GB per hour. Photos are far less demanding — about 200,000 phone JPEGs at 5 MB each, or 40,000 RAW files at 25 MB. Video is what fills drives, and anyone shooting 4K will exhaust a terabyte quickly.
Roughly 1.5 to 2 times the data you are protecting, to allow for versioning and growth. Remember also that the labelled capacity is about 7% optimistic in the units your operating system reports, and that formatting and any reserved or over-provisioned space consume a little more on top.
Why your 1 TB drive shows 931 GB
Buy a 1 TB hard drive, connect it to a Windows machine, and it reports roughly 931 GB. Nothing is wrong, nothing was lost, and no manufacturer is cheating — the two are using different definitions of the same prefix.
The manufacturer sells 1 TB decimal = 1,000,000,000,000 bytes. Windows divides that by 1,024 three times to reach what it calls GB but is actually GiB: 1,000,000,000,000 ÷ 1,024³ = 931.3.
Decimal: 1 TB = 1,000 GB Binary: 1 TiB = 1,024 GiB
The gap is 9.95% at this scale, and it widens with every step up the ladder — about 2.4% at KB, 4.9% at MB, 7.4% at GB, 9.95% at TB and 12.6% at PB.
The formatted capacity question
Beyond the prefix mismatch, a small further amount is genuinely consumed:
Filesystem overhead — the structures that track where files live typically consume a fraction of a percent to a few percent depending on the filesystem and allocation unit size.
Reserved space — some systems reserve a portion for recovery partitions or for the OS.
Over-provisioning on SSDs — drives reserve a hidden portion for wear levelling and bad-block management, which is why SSD usable capacities sometimes look odd.
So a 1 TB drive typically presents around 931 GiB before formatting and slightly less after.
Common values
Decimal:
- 500 GB = 0.5 TB
- 1,000 GB = 1 TB
- 2,000 GB = 2 TB
- 4,000 GB = 4 TB
As reported by Windows:
- 1 TB drive ≈ 931 GiB
- 2 TB drive ≈ 1,863 GiB
- 4 TB drive ≈ 3,726 GiB
- 8 TB drive ≈ 7,451 GiB
What a terabyte holds
Useful for sizing storage against actual needs:
- Photos at 5 MB each (a typical phone JPEG): about 200,000
- RAW photos at 25 MB: about 40,000
- Music at 5 MB per track: about 200,000 tracks
- 1080p video at roughly 4 GB per hour: about 250 hours
- 4K video at roughly 20 GB per hour of recorded footage: about 50 hours
Video is what fills drives. Anyone shooting 4K will exhaust a terabyte far faster than they expect.
Buying advice this implies
If you need a genuine terabyte of usable binary space, buy a 1.2 TB or larger decimal drive, or simply accept that the labelled figure is about 7% optimistic in the units your operating system will report.
For backup purposes, size the destination at roughly 1.5 to 2 times the data you are protecting, to allow for versioning and growth.