Storage Standards Explained
SI (Decimal) Standard
Uses base-10 (decimal) system. Commonly used by storage manufacturers and in marketing.
Example:
1 KB = 1,000 bytes1 MB = 1,000,000 bytes
1 GB = 1,000,000,000 bytes
IEC (Binary) Standard
Uses base-2 (binary) system. Used by operating systems and software for actual storage.
Example:
1 KiB = 1,024 bytes1 MiB = 1,048,576 bytes
1 GiB = 1,073,741,824 bytes
| Comparison | SI (Decimal) | IEC (Binary) |
|---|---|---|
| Base System | 103 = 1,000 | 210 = 1,024 |
| Used By | Hard drive manufacturers | Operating systems (Windows/Mac) |
| Common Use | Marketing, packaging | Actual file storage |
| Key Difference | 1 GB ≈ 0.931 GiB (about 7% smaller) | |
?? Practical Example: A "1TB" hard drive (SI) shows as "931GB" in Windows (IEC).
This 7% difference explains why your drive seems smaller than advertised!