Two systems, similar names
The SI (decimal) system defines each step as ×1000: 1 kB = 1000 bytes, 1 MB = 1,000,000, 1 GB = 1,000,000,000. Storage manufacturers and network speeds use this.
The binary system defines each step as ×1024, and uses the -bi- names: 1 KiB = 1024 bytes, 1 MiB = 1,048,576, 1 GiB = 1,073,741,824. Most operating systems report memory and file sizes this way, often still labelling them "KB/MB/GB".
The gap grows with size
Because 1024 is 2.4% more than 1000, and it compounds at every step:
- •1 KB vs 1 KiB — about 2% apart.
- •1 GB vs 1 GiB — about 7% apart.
- •1 TB vs 1 TiB — about 10% apart (1 TB ≈ 0.909 TiB).
Convert between them
The Data Size Converter has both sets of units, so you can put in 1 GB and read off the GiB value, or go the other way.
- •Data Size Converter — decimal and binary units side by side.
Last updated September 4, 2026.