Gibibytes and gigabytes
A gibibyte (GiB) is 1,024 MiB, or 1,073,741,824 bytes, about 7.4% more than a gigabyte. Windows reports drive and file sizes in GiB while labeling them GB; cloud VMs and RAM are sized in GiB.
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.
Worked example
Convert 16 GiB: 16 × 1.073741824 = 17.17986918, so 16 gibibytes is 17.17986918 gigabytes. Likewise 20 GiB = 21.47483648 GB.
Estimating in your head
Multiply by 1.1 for a quick figure; it is off by about 2.4%. For 16 GiB that gives 17.6 GB, against 17.1799 exactly.
Going the other way
To convert gigabytes to gibibytes, divide by 1.073741824 (or multiply by 0.931322574615).
How this works
GB = GiB × 1.073741824
1 GiB = 1,073,741,824 B and 1 GB = 1,000,000,000 B, both by definition, so the factor is their ratio: 1.073741824 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 gigabytes are in a gibibyte?
1 gibibyte = 1.073741824 gigabytes, exactly. The value follows from the unit definitions, so it never changes.
How do I convert gibibytes to gigabytes?
Multiply by 1.073741824. For example, 20 GiB × 1.073741824 = 21.47483648 GB.
What is 100 GiB in gigabytes?
100 GiB = 107.3741824 GB. 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/gib-to-gb/