Data Size Converter
Convert between data storage and transfer units for both decimal (SI) and binary (IEC) standards. Understand the difference between gigabytes (GB, 10^9) and gibibytes (GiB, 2^30) that causes confusion with hard drive sizes. Live grid shows your value in bits, bytes, and all common prefixed units simultaneously.
What does this tool do?
The Data Converter clarifies the often-confusing world of digital storage units. It shows both SI decimal units (powers of 1000: KB, MB, GB, TB, PB) and IEC binary units (powers of 1024: KiB, MiB, GiB, TiB, PiB) side-by-side. This explains why a 1 TB hard drive shows as ~931 GB in Windows — drive makers use decimal TB, Windows uses binary GiB (though it labels it GB). The tool also converts to bits for network speed calculations, helping understand the difference between Mbps (megabits per second) and MB/s (megabytes per second).
How it works
SI units use powers of 1000: 1 KB = 1000 bytes, 1 MB = 1000 KB = 1,000,000 bytes, etc. IEC units use powers of 1024: 1 KiB = 1024 bytes, 1 MiB = 1024 KiB = 1,048,576 bytes, etc. The base unit is the byte (8 bits). Conversions go through bytes: input → bytes → all other units. For example: 1 GB (SI) = 1,000,000,000 bytes = 953.674 MiB (IEC). The tool clearly labels SI vs IEC to avoid confusion. Network speeds are typically in bits per second (divide bytes by 8 to get bits).
Features
- Both SI (decimal, 1 KB = 1000 B) and IEC (binary, 1 KiB = 1024 B)
- Bits and bytes both available
- Live multi-unit grid display
- Tooltip explains the discrepancy
- Copy any value with one click
- Shows why drive sizes appear smaller
- Network speed vs file size conversion
How to use
- 1
Enter a value
Type in any unit field — GB for drive capacity, MB for file sizes, Mbps for network speeds.
- 2
Compare SI vs IEC
1 GB (decimal) ≠ 1 GiB (binary). Notice the ~7% difference that explains 'missing' hard drive space.
- 3
Convert to bits for network
ISP speeds are in megabits per second (Mbps). File sizes are in megabytes (MB). Divide bits by 8 to get bytes.
- 4
Copy needed format
Click any unit to copy the value for your specification, purchase decision, or technical documentation.
Common use cases
Hard drive capacity understanding
Understand why your 1 TB drive shows as 931 GB — the difference between manufacturer decimal TB and operating system binary GiB.
Network speed calculations
Convert between Mbps (megabits per second advertised by ISPs) and MB/s (megabytes per second you'll see in downloads).
File storage planning
Calculate how many files fit on a storage device by converting between file sizes in MB/GB and device capacity.
Technical specification writing
Get precise values in the correct unit system (SI vs IEC) for accurate technical documentation and requirements.
Tips & best practices
- Drive manufacturers use decimal (GB = 10^9). Windows uses binary but labels as GB when it means GiB (2^30). This creates the 'missing space' perception
- macOS and Linux typically use IEC binary units (MiB, GiB) correctly labeled, or allow user preference
- Network speeds are always bits: 100 Mbps = 100 megabits per second = 12.5 megabytes per second theoretical max
- 1 byte = 8 bits. To convert file size (bytes) to download time: divide by (speed in bits / 8)