GB vs GiB: Gigabyte vs Gibibyte Explained

5 min read•June 1, 2026•Reviewed: June 1, 2026

✓Reviewed by Apex Conversion Editorial Team · Last reviewed June 1, 2026

GB stands for gigabyte: 1 GB = 1,000,000,000 bytes (1 billion bytes, 10⁹). GiB stands for gibibyte: 1 GiB = 1,073,741,824 bytes (2³⁰). The gap is 73,741,824 bytes — about 7.4%. This is why a '1 TB' (1,000 GB) solid-state drive shows as approximately 931 GiB in most operating systems. The storage is all there; the discrepancy is entirely in which definition of 'giga' each party uses.

The word 'gigabyte' alone is ambiguous — without context, you cannot know if someone means 10⁹ or 2³⁰. The IEC introduced 'gibibyte' (GiB) in 1998 to resolve this, but adoption has been slow and inconsistent. Knowing which convention applies in a given situation prevents planning errors and user frustration.

GB vs GiB Conversions

1 GB  = 1,000,000,000 bytes (10⁹, SI decimal)
1 GiB = 1,073,741,824 bytes (2³⁰, IEC binary)

1 GiB = 1.073741824 GB
1 GB  = 0.931322574 GiB  (≈ 0.93 GiB)

Practical drive capacity examples:
  256 GB SSD  → OS shows ~238 GiB
  512 GB SSD  → OS shows ~477 GiB
  1,000 GB HDD → OS shows ~931 GiB
  2,000 GB HDD → OS shows ~1,863 GiB

Why the Gap Grows at Higher Capacities

At the kilo level, the decimal vs binary gap is 2.4% (1,024 vs 1,000). At mega, 4.9%. At giga, 7.4%. At tera, 10.0%. At peta, 12.6%. Each prefix level compounds the discrepancy: 1 TiB = 1,024 GiB = 1,024 × 1,024 MiB = 1,099,511,627,776 bytes, while 1 TB = 1,000,000,000,000 bytes. The difference grows because binary multiplies the gap with each successive power of 1,024.

This means the larger the storage device, the more prominent the 'missing space' appears. A 4 TB drive shows as about 3.64 TiB — a visible 360 GiB gap. A 16 TB drive shows as 14.55 TiB. None of that capacity is actually missing; it is all there on the drive, accessible and usable. The labeling mismatch is a consumer-visible consequence of two different counting systems in the same ecosystem.

Frequently Asked Questions

Why do operating systems use GiB instead of GB?

Because RAM and CPU architectures are binary — memory is addressed in powers of 2. Historically, OS developers used binary sizes and called them 'KB/MB/GB' because there were no separate binary prefix terms until 1998. The habit stuck for storage display even though drives use decimal. macOS switched to decimal labeling in 2016; most Linux distributions use binary (GiB) correctly.

How much is '1 gig' of storage?

'1 gig' informally means 1 GB to most people — 1,000,000,000 bytes in modern usage. In an OS display, '1 GB' might mean 1 GiB (1,073,741,824 bytes). In practice, treat 1 GB ≈ 1 GiB for everyday estimation — the 7.4% difference only matters when planning storage to the gigabyte.

Is my 256 GB phone really 256 GB?

The manufacturer's '256 GB' means 256,000,000,000 bytes (decimal). Your OS will show this as approximately 238 GiB — sometimes still labeled 'GB.' Additionally, the phone's OS and preloaded apps occupy some of that storage, further reducing available user space.

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