File Size Converter
Convert between bytes, KB, MB, GB, TB and PB instantly — choose decimal (1000-based) or binary (1024-based) units.
Disclaimer. Decimal and binary unit systems give different byte counts for the same labeled size (e.g. 1 GB decimal vs 1 GiB binary). Choose the mode that matches how your source figure was measured for an accurate conversion. Read full disclaimer →
Decimal vs Binary File Size Units
There are two competing conventions for file size units. Decimal (SI) units, used by hard drive and SSD manufacturers, scale by 1000: 1 KB = 1,000 bytes, 1 MB = 1,000,000 bytes, and so on. Binary units, used internally by most operating systems, scale by 1024: 1 KiB = 1,024 bytes, 1 MiB = 1,048,576 bytes. This converter lets you toggle between both.
| Unit | Decimal (base 1000) | Binary (base 1024) |
|---|---|---|
| Kilobyte | 1,000 bytes | 1,024 bytes |
| Megabyte | 1,000,000 bytes | 1,048,576 bytes |
| Gigabyte | 1,000,000,000 bytes | 1,073,741,824 bytes |
| Terabyte | 1,000,000,000,000 bytes | 1,099,511,627,776 bytes |
Worked Example
A "1 TB" hard drive advertised in decimal units contains exactly 1,000,000,000,000 bytes. When Windows reports this same drive's capacity using binary units, it divides by 1,073,741,824 (1024³), showing roughly 931 GiB — which is why your "1TB" drive never shows a full 1000GB of usable space in File Explorer.