How to convert terabytes (TB) to gigabytes (GB)
Multiply terabytes by 1,000: a 4 TB drive is 4,000 GB. To see what Windows will report, convert TB to GiB: 4 TB ≈ 3,725 GiB.
Decimal (MB) vs binary (MiB) units
Storage makers, networks and macOS use decimal units: 1 KB = 1,000 bytes, 1 MB = 1,000 KB, 1 GB = 1,000 MB. Windows and many programs count in binary units (1 KiB = 1,024 bytes, 1 MiB = 1,024 KiB), but still label them "KB", "MB" and "GB". That's why a "1 TB" drive shows as about 931 GB in Windows. Choose the KiB/MiB/GiB options above to convert the binary way.
Terabytes (TB) to gigabytes (GB) table
- 0.25 terabytes (TB) = 250 gigabytes (GB)
- 0.5 terabytes (TB) = 500 gigabytes (GB)
- 1 terabytes (TB) = 1,000 gigabytes (GB)
- 2 terabytes (TB) = 2,000 gigabytes (GB)
- 4 terabytes (TB) = 4,000 gigabytes (GB)
- 5 terabytes (TB) = 5,000 gigabytes (GB)
- 8 terabytes (TB) = 8,000 gigabytes (GB)
- 10 terabytes (TB) = 10,000 gigabytes (GB)
- 16 terabytes (TB) = 16,000 gigabytes (GB)
- 20 terabytes (TB) = 20,000 gigabytes (GB)
Frequently asked questions
Why does my 1 TB drive show 931 GB?
The drive is 1,000,000,000,000 bytes. Windows divides by 1,024³ and gets about 931 GiB, but labels it "GB".
How do I convert gigabytes (GB) back to terabytes (TB)?
Press "Swap units" and type your value. The same factor is applied in reverse.
Is the result exact?
Yes. Results use the exact defined factors and show up to 8 decimal places.
How to use the TB to GB Converter
- Type a number in the input box.
- Choose decimal (1000) or binary (1024) if the tool offers both.
- Read the converted value instantly.
- Use the reference table below for common values.
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Formulas, tables and sources on the page.
TB to GB Converter: chart and reference data
Source: NIST – Prefixes for binary multiples (exact arithmetic: 1024ⁿ ÷ 1000ⁿ − 1)
| TB | GB (decimal, 1000-based) | GB (binary, 1024-based) |
|---|---|---|
| 1 | 1,000 | 1,024 |
| 5 | 5,000 | 5,120 |
| 10 | 10,000 | 10,240 |
| 50 | 50,000 | 51,200 |
| 100 | 100,000 | 102,400 |
| 500 | 500,000 | 512,000 |
| 1,000 | 1,000,000 | 1,024,000 |
TB to GB Converter compared with the alternatives
| Convention | Base | 1 GB / GiB in bytes | Used by |
|---|---|---|---|
| SI decimal (kB, MB, GB) | 1000 | 1,000,000,000 | Drive makers, macOS, networking |
| IEC binary (KiB, MiB, GiB) | 1024 | 1,073,741,824 | Windows (labelled GB), RAM, Linux tools |
Who uses it in the UK
- Checking if a file fits an email attachment limit
- Understanding phone, cloud and drive storage
- Planning backups and uploads
- Developers sizing logs and databases
More questions
Why does my 1 TB drive show about 931 GB?
Drive makers use decimal units (1 TB = 10¹² bytes) while Windows reports binary units but labels them GB. 10¹² ÷ 2³⁰ ≈ 931.3, so nothing is missing.
What is the difference between MB and MiB?
MB (megabyte) is 1,000,000 bytes in the SI system. MiB (mebibyte) is 1,048,576 bytes (2²⁰). The IEC introduced the "bi" prefixes in 1998 to remove the ambiguity.
Is internet speed measured in MB?
Usually not. Broadband speeds are quoted in megabits per second (Mbps). Divide by 8 to get megabytes per second, so 80 Mbps is about 10 MB/s.
Which convention does macOS use?
Since Mac OS X 10.6, macOS reports file and disk sizes in decimal units (1 GB = 1,000,000,000 bytes), so they match the number on the box.
Further reading: IEC – Binary prefixes
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