What's the difference between decimal (KB) and binary (KiB)?

Decimal units use powers of 1000: 1 KB = 1,000 bytes, 1 MB = 1,000,000 bytes. Binary units use powers of 1024: 1 KiB = 1,024 bytes, 1 MiB = 1,048,576 bytes. Storage manufacturers advertise in decimal, but Windows/macOS/Linux typically report file sizes in binary.

Why does my 1 TB drive show as 931 GB in Windows?

The drive has 1,000,000,000,000 bytes (decimal TB). Windows displays this in binary (GiB), so it shows 1e12 / 2^30 ≈ 931.32 GB. The drive isn't smaller — just measured differently.

Which should I use for bandwidth calculations?

Network speeds (Mbps, Gbps) are decimal and measured in bits, not bytes. Divide by 8 to get bytes per second. For example, 1 Gbps ≈ 125 MB/s (decimal) of throughput.

Data Size Converter (Bytes, KB, MB, GB, TB)

Converters· 6 tools

Free data size converter. Enter a value in any unit and instantly see it in bytes, KB, MB, GB, TB, and PB. Switch between decimal (SI, 1 KB = 1000 B) — used by storage manufacturers and network specs — and binary (IEC, 1 KiB = 1024 B) — used by most operating systems. Handy for sizing backups, bandwidth plans, or converting disk quotas.

Value

Unit

System

Bytes (B)1,000,000,000

Kilobytes (KB)1,000,000

Megabytes (MB)1,000

Gigabytes (GB)1

Terabytes (TB)0.001

Petabytes (PB)1.0000e-6

Decimal (SI): 1 KB = 1,000 B. Used by storage manufacturers, network speeds (Mbps), and most marketing specs.

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