⚖️ 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 (since Snow Leopard) and many Linux tools.

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 binary prefixes (1998-99), now IEC 80000-13

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. This comparison is general guidance based on publicly available information. Prices, rates, rules and specifications change, so check current details with the provider or an official source before making a decision. 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.

Frequently asked questions

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.

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.