Decimal vs binary units
Storage makers use decimal (SI) units: 1 KB = 1,000 bytes, 1 GB = 1,000,000,000 bytes. Windows, and many other programs, count in binary units (1 KiB = 1,024 bytes, 1 GiB = 1,073,741,824 bytes) but label them "KB", "MB" and "GB".
That is why a 1 TB drive shows as about 931 GB in Windows: 10¹² bytes ÷ 1,073,741,824 = 931.3 GiB. No space is missing.
| Decimal | Bytes | Binary | Bytes |
|---|---|---|---|
| 1 KB | 1,000 | 1 KiB | 1,024 |
| 1 MB | 1,000,000 | 1 MiB | 1,048,576 |
| 1 GB | 10⁹ | 1 GiB | 1,073,741,824 |
| 1 TB | 10¹² | 1 TiB | 1,099,511,627,776 |
Bits vs bytes (internet speed)
Internet speeds are quoted in megabits per second (Mbps), and file sizes in megabytes. There are 8 bits in a byte, so a 100 Mbps connection downloads at most about 12.5 MB per second.
Frequently asked questions
Is 1 GB 1000 MB or 1024 MB?
Both are used. In the SI standard, 1 GB = 1,000 MB. In binary, 1 GiB = 1,024 MiB. Operating systems often show binary values with decimal labels.
How long will a 1 GB download take at 50 Mbps?
1 GB = 8,000 megabits. 8,000 ÷ 50 = 160 seconds, about 2.7 minutes, at full speed.
Conversions use standard factors and are for general information. Exchange rates are indicative and may differ from rates offered by banks.
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