💾 Byte Size Converter – SI & IEC Digital Storage Units
The Byte Size Converter translates digital storage sizes between all standard units — bits, bytes, kilobytes, megabytes, gigabytes, terabytes, petabytes, and exabytes — covering both SI (decimal, base-10) and IEC (binary, base-2) standards simultaneously. Whether you are sizing memory buffers, calculating network throughput, verifying disk capacity, or simply trying to understand why your "1 TB" drive shows less space in Windows, this tool gives you instant, accurate answers.
SI vs IEC: Why Two Standards Exist
The confusion around storage sizes stems from two competing conventions that use similar-sounding names but different multipliers:
| Standard | Base | Unit Example | Factor | Typical Use |
|---|---|---|---|---|
| SI | Base-10 (decimal) | 1 GB | 1,000,000,000 bytes | Storage manufacturers, network speeds |
| IEC | Base-2 (binary) | 1 GiB | 1,073,741,824 bytes | Operating systems, RAM, compilers |
The gap widens at larger units: at the gigabyte scale the difference is ~7.4 %, and at the terabyte scale it grows to nearly 10 %. This is why a drive labelled "1 TB" (SI: 10¹² bytes) displays as only about 931 GiB in Windows — no storage has been lost, it is purely a unit mismatch.
Supported Units
| Symbol | Full Name | Standard | Factor (bytes) |
|---|---|---|---|
b | Bit | — | 1/8 |
B | Byte | — | 1 |
KB | Kilobyte | SI | 10³ = 1,000 |
KiB | Kibibyte | IEC | 2¹⁰ = 1,024 |
MB | Megabyte | SI | 10⁶ = 1,000,000 |
MiB | Mebibyte | IEC | 2²⁰ = 1,048,576 |
GB | Gigabyte | SI | 10⁹ = 1,000,000,000 |
GiB | Gibibyte | IEC | 2³⁰ = 1,073,741,824 |
TB | Terabyte | SI | 10¹² |
TiB | Tebibyte | IEC | 2⁴⁰ |
PB | Petabyte | SI | 10¹⁵ |
PiB | Pebibyte | IEC | 2⁵⁰ |
EB | Exabyte | SI | 10¹⁸ |
EiB | Exbibyte | IEC | 2⁶⁰ |
How the Conversion Works
The algorithm follows three steps:
- Parse input: read the numeric value and source unit (e.g., 1.5 GB).
- Convert to bytes: multiply by the source unit factor (
1.5 × 10⁹ = 1,500,000,000 bytes). - Divide by each target factor: for every output unit, divide the raw byte count by that unit's factor (
÷ 2³⁰for GiB gives≈ 1.3970 GiB).
For bits: multiply bytes by 8 (there are always exactly 8 bits per byte). The best-fit formatter scans from the largest unit downward and picks the first unit whose converted value is ≥ 1, producing a compact human-readable result.
Network Bandwidth Conversions
Network speeds are quoted in bits per second (bps, Kbps, Mbps, Gbps), while file transfer progress is shown in bytes per second. To convert, divide by 8: 100 Mbps ÷ 8 = 12.5 MB/s. Select Mb as your input unit and the table will show both the bit-level and byte-level equivalents across all scales.
Practical Examples
| Scenario | Input | SI Result | IEC Result |
|---|---|---|---|
| 4K video file | 50 GB | 50,000 MB | 46.566 GiB |
| RAM size | 16 GiB | 17.179 GB | 16,384 MiB |
| Floppy disk | 1.44 MB | 1,440 KB | 1.373 MiB |
| Internet speed | 1 Gb (gigabit) | 125 MB/s equivalent | 119.2 MiB/s equivalent |
Bulk Conversion Mode
The Bulk / Multi-Row tab accepts multiple values — one per line — optionally followed by a unit symbol (e.g., 512 MiB). If no unit is specified, bytes are assumed. Each line is converted independently and the results appear in a scrollable comparison grid, ideal for processing file-size lists from directory listings or log files.
When to Use Each Standard
- SI units (KB, MB, GB…) — use when communicating with storage manufacturers, reading drive specifications, or working with network bandwidth figures.
- IEC units (KiB, MiB, GiB…) — use when working with operating system reports, programming languages that allocate memory in powers of two, or when precision matters in technical documentation.
- Bits (b, Kb, Mb…) — use for all network throughput and interface speed calculations.