What is the difference between KB and KiB?

KB (kilobyte) is 1,000 bytes using SI decimal units, while KiB (kibibyte) is 1,024 bytes using binary IEC units. Hard drive manufacturers use KB (1000), while operating systems typically display file sizes in KiB (1024).

Why does my hard drive show less space than advertised?

Hard drive manufacturers use SI decimal units (1 GB = 1,000,000,000 bytes) while operating systems use binary units (1 GiB = 1,073,741,824 bytes). A 1 TB drive has 1,000,000,000,000 bytes but shows as 931 GiB in your OS.

💾 Byte Converter

Convert between Bytes, KB, MB, GB, TB, and PB. Toggle between binary (1024) and SI (1000) units.

Binary (KiB, MiB — ×1024) SI/Decimal (KB, MB — ×1000)

Bytes (B)

Kilobytes (KB)

Megabytes (MB)

Gigabytes (GB)

Terabytes (TB)

Petabytes (PB)

Understanding Data Size Units – Binary (1024) vs SI Decimal (1000)

Confusion between binary and decimal data units is one of the most common sources of misunderstanding in computing. When you buy a "500 GB" hard drive, you get 500,000,000,000 bytes (SI decimal), but your operating system shows ~465 GiB (binary). This tool supports both systems for accurate conversion.

Binary Units (IEC Standard – Base 1024)

1 KiB (kibibyte) = 1,024 bytes — Used by operating systems (Windows, macOS, Linux) for file sizes and RAM
1 MiB (mebibyte) = 1,048,576 bytes (1024²)
1 GiB (gibibyte) = 1,073,741,824 bytes (1024³) — What your OS shows for RAM and disk space
1 TiB (tebibyte) = 1,099,511,627,776 bytes (1024⁴)

SI Decimal Units (Base 1000)

1 KB (kilobyte) = 1,000 bytes — Used by hard drive manufacturers, network speeds, and ISPs
1 MB (megabyte) = 1,000,000 bytes (1000²)
1 GB (gigabyte) = 1,000,000,000 bytes (1000³) — What hard drive labels show
1 TB (terabyte) = 1,000,000,000,000 bytes (1000⁴)

Why Your Hard Drive Shows Less Space Than Advertised

Hard drive manufacturers use SI decimal units (1 GB = 1,000,000,000 bytes) while operating systems display file sizes in binary units (1 GiB = 1,073,741,824 bytes). A "1 TB" drive contains 1,000,000,000,000 bytes, but the OS shows 931 GiB. The "missing" 69 GiB isn't lost — it's the difference between the two measurement systems.

Common Data Size References

1 page of text ≈ 2 KB
1 high-res photo (JPEG) ≈ 3–5 MB
1 minute of MP3 audio ≈ 1 MB (128 kbps)
1 minute of 1080p video ≈ 150 MB
1 hour of 4K Netflix streaming ≈ 7 GB
Average game download (2024) ≈ 50–100 GB