⚖️ Comparison · Updated for 2026
GB (gigabyte) vs GiB (gibibyte)
Side-by-side comparison, when-to-use-each guide, and instant conversion. Reviewed for 2026.
Quick answer: 1 GB = 10⁹ bytes (1,000,000,000) — decimal, used by storage manufacturers and broadband providers. 1 GiB = 2³⁰ bytes (1,073,741,824) — binary, used by Windows, RAM specs, and most operating systems. This 7% difference is why your '1 TB' hard drive shows as 931 GB.
Decision guide — when to use which
Use GB (gigabyte) when…
Hard drive marketing, broadband contracts, mobile data plans, file size displays on macOS Catalina+ and Linux.
Use GiB (gibibyte) when…
Windows file sizes, RAM modules, technical documentation, IEEE/IEC standards.
📊 Side-by-side comparison
| Aspect | GB (gigabyte) | GiB (gibibyte) |
|---|---|---|
| Definition | 10⁹ bytes (decimal) | 2³⁰ bytes (binary) |
| 1 unit equals | 1,000,000,000 bytes | 1,073,741,824 bytes |
| Difference | — | 7.4% more bytes than GB |
| Used by | Storage marketing, broadband | OS file managers (Windows), RAM |
| Standardised | SI prefix system | IEC 80000-13 (1999) |
Frequently asked
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Why does my 1 TB drive show as 931 GB?
Drive makers use decimal TB (10¹² bytes). Windows uses binary TiB (2⁴⁰ bytes) but labels it 'TB'. The drive really does have 1,000,000,000,000 bytes — which is 931 GiB.
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Should I use GB or GiB?
For technical writing, GiB is more precise. For consumer language, GB is universal — just be aware which definition is in play in any given context.
Reviewed for 2026. All conversion factors and historical references verified against official sources (ISO standards, government weights & measures legislation, IEC technical specifications). Built by a UK-based qualified primary teacher and FA Level 2 coach as part of 247QuickTools' free utility-tools project. We don't sell SEO links or accept paid placements in this content.