GB to TB: Gigabytes to Terabytes Converter
Both conventions shown, and the reason a 1 TB drive reports as 931 GB.
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- 500 GB0.500 TB0.488 TiB
- 1,000 GB1.000 TB0.977 TiB
- 1,024 GB1.024 TB1.000 TiB
- 2,000 GB2.000 TB1.953 TiB
- 4,000 GB4.000 TB3.906 TiB
- 8,000 GB8.000 TB7.812 TiB
- 16,000 GB16.000 TB15.625 TiB
- 512 GB0.512 TB0.500 TiB
- 256 GB0.256 TB0.250 TiB
Why the gap is worse up here
The decimal and binary conventions diverge by 2.4 percent at each step, and the steps compound. By the terabyte the gap is about 10.0 percent, which is why the discrepancy on a large drive looks alarming when the same effect on a memory card doesn't.
1,000,000,000,000 bytes ÷ 1024⁴ = 0.909 TB (binary)
Formatting also reserves some space for filesystem structures, which is a real reduction on top of the arithmetic one, though usually much smaller.
Conversion table
| Gigabytes | TB (decimal) | TB (binary) | As sold / as reported |
|---|---|---|---|
| 500 GB | 0.500 | 0.488 | 0.5 TB drive |
| 1,000 GB | 1.000 | 0.977 | 1 TB drive shows ~0.93 |
| 2,000 GB | 2.000 | 1.953 | 2 TB drive shows ~1.86 |
| 4,000 GB | 4.000 | 3.906 | 4 TB drive shows ~3.73 |
| 8,000 GB | 8.000 | 7.812 | 8 TB drive shows ~7.45 |
| 16,000 GB | 16.000 | 15.625 | 16 TB drive shows ~14.9 |
Common questions
Why does my 1 TB drive show as 931 GB?
Because it holds a trillion bytes, which the manufacturer counts as 1 TB decimal, while your operating system divides by 1,024 four times and reports about 931 GB. Nothing is missing.
Is 1 TB 1000 GB or 1024 GB?
1,000 under the decimal convention used by manufacturers and the SI, 1,024 under the binary convention used by most operating systems.
How big is the gap at this step?
About 10.0 percent by the terabyte, up from 2.4 percent at the kilobyte. The difference compounds at every step.
What is a tebibyte?
The IEC name for the binary terabyte, 1,024 gibibytes. Almost no consumer software uses the name, which is why the ambiguity persists.
Related converters and guides
Sources
- The binary prefixes kibi, mebi, gibi and tebi are defined by the International Electrotechnical Commission, not by the SI. The decimal prefixes kilo, mega, giga and tera are SI and are always powers of 1,000.
- NIST Guide to the SI, Appendix B: Conversion Factors. National Institute of Standards and Technology. Source for every conversion factor on this page, and for which factors are exact rather than rounded.