Digital Storage Guide
Why your 500GB drive shows less space, plus bits vs bytes and binary vs decimal explained
Overview
Digital storage is measured in bytes and their multiples. Understanding these units is essential for managing files, choosing storage devices, and understanding internet speeds.
There are two standards: binary (used by computers) and decimal (used by storage manufacturers), which can cause confusion about actual storage capacity.
The Basics: Bits and Bytes
Bit (b)
The smallest unit of data. A bit can be either 0 or 1.
Used primarily for measuring data transfer speeds (e.g., Mbps).
Byte (B)
1 Byte = 8 bits
The fundamental unit for measuring file sizes and storage capacity.
One byte can represent a single character (like "A" or "7").
Binary vs Decimal: The Confusion
This is why your "500 GB" hard drive shows less space than expected!
| Unit | Decimal (SI) | Binary (IEC) | Difference |
|---|---|---|---|
| Kilo- | 1 KB = 1,000 B | 1 KiB = 1,024 B | 2.4% |
| Mega- | 1 MB = 1,000,000 B | 1 MiB = 1,048,576 B | 4.9% |
| Giga- | 1 GB = 1,000,000,000 B | 1 GiB = 1,073,741,824 B | 7.4% |
| Tera- | 1 TB = 10^12 B | 1 TiB = 2^40 B | 10% |
Example: A "1 TB" hard drive (decimal) = 931 GiB when your computer displays it (binary). You are not missing storage - it is just measured differently!
Real-World File Sizes
~5 KB Plain text email
~500 KB Word document
~3 MB MP3 song (3 min)
~5 MB Smartphone photo
~700 MB CD of data
~1.5 GB HD movie
~4.7 GB DVD
~50 GB 4K movie / Game