Gigabytes and terabytes
A gigabyte (GB) is 1,000,000,000 bytes, or 1,000 MB, in the decimal system. Phone storage, data plans, RAM and video files are measured in gigabytes.
A terabyte (TB) is 10¹² bytes, or 1,000 GB, in the decimal system. Hard drives, SSDs, backups and cloud storage plans are sold in terabytes.
Worked example
Convert 500 GB: 500 × 0.001 = 0.5, so 500 gigabytes is 0.5 terabytes. Likewise 100 GB = 0.1 TB.
Estimating in your head
The factor is a power of ten, so just move the decimal point 3 places to the left: 500 GB = 0.5 TB.
Going the other way
To convert terabytes to gigabytes, divide by 0.001 (or multiply by 1,000). The swap button between the boxes opens that page.
How this works
TB = GB × 0.001
1 GB = 1,000,000,000 B and 1 TB = ≈ 1,000,000,000,000 B, both by definition, so the factor is their ratio: 0.001 exactly. Results drop binary floating-point noise beyond 15 significant digits and display at the precision you choose (6 significant figures by default). Copy result copies the full value.
Frequently asked
How many terabytes are in a gigabyte?
1 gigabyte = 0.001 terabytes, exactly. The value follows from the unit definitions, so it never changes.
How do I convert gigabytes to terabytes?
Multiply by 0.001. For example, 100 GB × 0.001 = 0.1 TB.
What is 1,000 GB in terabytes?
1,000 GB = 1 TB. The table next to the converter lists more common values.
Is the result rounded?
Only on screen. The page computes with the exact definitions and removes floating-point noise past 15 significant digits; pick 3 to 12 significant figures, or use Copy result for the full value.
Sources
- NIST — Prefixes for binary multiples (IEC 80000-13)
- BIPM — The International System of Units (SI Brochure), 9th edition
- Wikipedia — Byte
Reviewed Oct 17, 2026 · test vectors fixtures/units/data/gb-to-tb/