MB vs GB vs TB
The three data-storage tiers everyone meets — and how SI decimal differs from binary IEC units.
| Megabyte (MB) | Gigabyte (GB) | Terabyte (TB) | |
|---|---|---|---|
| SI decimal | 10⁶ = 1,000,000 B | 10⁹ B | 10¹² B |
| Binary (IEC) | MiB = 2²⁰ ≈ 1.049 MB | GiB = 2³⁰ ≈ 1.074 GB | TiB = 2⁴⁰ ≈ 1.1 TB |
| Typical use | Photo, MP3 | HD movie, OS install | Drive, cloud bucket |
| 1 of the next | 1,000 MB = 1 GB | 1,000 GB = 1 TB | — |
- Matches consumer file sizes
- Easy mental math
- Standard SaaS pricing tier
- Default unit for SSDs
When to use which
Use MB for individual files and email attachments.
Use GB for OS, application installs, RAM sizing, and cloud storage budgets.
Historical context
The decimal-vs-binary split crystallized in 1998 when the IEC introduced KiB / MiB / GiB to end the ambiguity. Storage vendors had quietly switched to decimal years earlier — which is why your drive 'shrinks' when Windows formats it.
Practical recommendation
Related tools
FAQs
Why does my 1 TB drive show 931 GB?+
Drive makers use SI TB (10¹² bytes); operating systems display in TiB (2⁴⁰ bytes), which is ~9.1% smaller.
Is RAM measured in GiB or GB?+
RAM is universally GiB (binary). 16 GB RAM is actually 16 GiB ≈ 17.18 GB in decimal.
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