File Size Converter
Convert between bytes, KB, MB, GB and TB — decimal or binary.
| Unit | Decimal (÷1000) | Binary equivalent |
|---|---|---|
| B | 10,00,000 | 10,00,000 B |
| KB | 1,000 | 976.5625 KiB |
| MB | 1 | 0.953674 MiB |
| GB | 0.001 | 0.000931 GiB |
| TB | 0.000001 | 0.000001 TiB |
| PB | 0 | 0 PiB |
1 MB = 10,00,000 bytes
Time to transfer
At the full advertised line rate. Real transfers are slower — protocol overhead, contention and the far end’s own limits all take a share.
Storage is sold in decimal units (1 GB = 1,000,000,000 bytes) but Windows reports binary ones and calls them GB, which is why a “1 TB” drive shows up as about 931 GB.
Convert between bytes, kilobytes, megabytes, gigabytes, and terabytes, correctly distinguishing between the decimal (1000-based) and binary (1024-based) definitions that cause the classic mismatch between what an OS reports and what a manufacturer advertises.
That distinction is exactly why a '1 TB' hard drive shows up as roughly 931 GiB in your operating system — both numbers are correct, they're just using different definitions of a gigabyte.
Decimal and binary units side by side
| Decimal (SI) | Bytes | Binary (IEC) | Bytes | Gap |
|---|---|---|---|---|
| 1 KB | 1,000 | 1 KiB | 1,024 | 2.4% |
| 1 MB | 1,000,000 | 1 MiB | 1,048,576 | 4.9% |
| 1 GB | 1,000,000,000 | 1 GiB | 1,073,741,824 | 7.4% |
| 1 TB | 10¹² | 1 TiB | 2⁴⁰ | 10.0% |
| 1 PB | 10¹⁵ | 1 PiB | 2⁵⁰ | 12.6% |
The discrepancy compounds — it's 2.4% at kilobyte scale and 10% at terabyte scale, which is why the 'missing' space on a large drive looks so alarming.
Who uses which
- Storage manufacturers use decimal. A '1 TB' drive genuinely contains 1,000,000,000,000 bytes.
- Windows reports binary but labels it with decimal units, showing that same drive as '931 GB' when it means GiB. This single labelling choice causes most of the confusion.
- macOS and most Linux distributions have used decimal units for years, so they report the drive as roughly 1 TB and match the box.
- RAM is always binary — memory addressing is inherently a power of two, so an 8 GB stick really is 8 GiB.
- Network speeds are decimal and measured in bits, not bytes: a 100 Mbps connection tops out around 12.5 MB/s.
Frequently asked questions
- Why does my hard drive show less space than advertised?
- Manufacturers advertise decimal units (1 GB = 1,000,000,000 bytes) while operating systems typically report binary units (1 GiB = 1,073,741,824 bytes), so a 1 TB drive shows as about 931 GiB in your OS.
- What's the difference between MB and MiB?
- MB (megabyte) is the decimal definition, 1,000,000 bytes; MiB (mebibyte) is the binary definition, 1,048,576 bytes. This tool lets you convert using either standard.
- Which standard should I use for file sizes in software?
- Use whichever matches the context — storage marketing typically uses decimal, while operating systems and RAM measurements typically use binary.
- Why is my 100 Mbps connection only downloading at 12 MB/s?
- Network speeds are quoted in bits per second, and there are 8 bits in a byte. 100 Mbps is about 12.5 MB/s at best, before protocol overhead.
- Is a megabit the same as a megabyte?
- No — a megabit is one eighth of a megabyte. The abbreviations differ only by case (Mb vs MB), which is why ISP marketing is so easy to misread.