How Data Storage Conversion Works
Data storage is measured in units based on powers of either 1,000 (decimal standard, used by storage manufacturers) or 1,024 (binary standard, used by operating systems). This difference is the reason a hard drive advertised as 1 TB appears as about 931 GB when you plug it into a Windows or macOS computer.
This converter lets you switch between both standards instantly. Select your input value and unit, choose binary or decimal, and see the complete conversion table to all other units in real time.
Binary vs Decimal Storage Standards
- Binary (IEC): 1 KB = 1,024 bytes, 1 MB = 1,048,576 bytes, 1 GB = 1,073,741,824 bytes
- Decimal (SI): 1 KB = 1,000 bytes, 1 MB = 1,000,000 bytes, 1 GB = 1,000,000,000 bytes
- Operating systems (Windows, macOS, Linux) use binary — this is why SSDs and HDDs appear smaller than advertised.
- Storage manufacturers, network providers, and ISPs use decimal — this maximises the number they can advertise.
Common Data Storage Reference Points
Understanding how storage units relate to real-world content helps you plan storage needs for devices, servers, backups, and cloud storage.
- 1 KB: a short text message or a small HTML file
- 1 MB: approximately one high-quality JPEG photo
- 1 GB: about 250 MP3 songs at 128 kbps, or 1,000 photos
- 1 TB: roughly 250,000 photos, 250 hours of HD video, or 1 million eBooks
- 1 PB: all US academic research libraries combined hold approximately 2 PB
Frequently Asked Questions
Why does my 1 TB hard drive show as 931 GB?
Hard drive manufacturers measure 1 TB as 1,000,000,000,000 bytes (decimal). Windows and macOS measure storage in binary, where 1 TB = 1,099,511,627,776 bytes. Dividing 1,000,000,000,000 by 1,073,741,824 (bytes per binary GB) gives approximately 931 GB — which is why your drive appears smaller than advertised. No capacity is lost; it is purely a labelling convention difference.
What is the difference between a bit and a byte?
A bit is the smallest unit of digital information — a single 0 or 1. A byte consists of 8 bits and can represent 256 different values. File sizes are always measured in bytes (or their multiples), while network and internet speeds are typically measured in bits per second (Mbps, Gbps). To convert download speeds: 100 Mbps ÷ 8 = 12.5 MB per second of actual file transfer speed.
What is the difference between KB and KiB?
Strictly speaking, KB (kilobyte) in the IEC standard refers to 1,000 bytes (decimal), while KiB (kibibyte) refers to 1,024 bytes (binary). However, in everyday usage, most software and documentation still use KB to mean 1,024 bytes, which creates confusion. This converter uses the more common informal convention: the 'binary' standard uses 1,024-based multiples.