Data Storage Converter

A drive marketed as 500 GB uses the decimal definition (1 GB = 1,000,000,000 bytes) and reports as about 465.66 GiB in an operating system that uses the binary definition (1 GiB = 1,073,741,824 bytes) but still labels it 'GB'. No storage is missing — the same bytes are being counted with two different-sized units.

Tip: “Copy with settings” shares a link that opens this calculator with your numbers already filled in.

How this calculator works

This converter covers both families of data storage units: decimal units (kilobyte, megabyte, gigabyte, terabyte), which use powers of 1000 and match the SI meaning of 'kilo', 'mega' and so on, and binary units (kibibyte, mebibyte, gibibyte, tebibyte), which use powers of 1024 and match how computer memory and file systems actually address storage in binary.

Drive manufacturers price and label capacity in decimal units (a '1 TB' drive has 1,000,000,000,000 bytes), which is also how the International System of Units defines the prefixes. Many operating systems, however, calculate free space in binary units but still print the label 'GB' or 'TB' instead of the correct 'GiB' or 'TiB' — that mislabeling, not any actual missing storage, is the entire source of the famous 'my new drive shows less space than advertised' complaint.

How it converts

result = value × (bits per from-unit) ÷ (bits per to-unit)Decimal: 1 KB = 1,000 B · 1 MB = 1,000² B · 1 GB = 1,000³ B · 1 TB = 1,000⁴ BBinary: 1 KiB = 1,024 B · 1 MiB = 1,024² B · 1 GiB = 1,024³ B · 1 TiB = 1,024⁴ B

Worked example: a 500 GB drive in GiB

500 GB (decimal, as sold) = 500 × 1,000,000,000 B = 500,000,000,000 bytes.
1 GiB (binary, as reported by the OS) = 1,073,741,824 bytes.
500,000,000,000 ÷ 1,073,741,824 ≈ 465.66 GiB.
The operating system displays this as '465.66 GB' — the bytes match exactly; only the unit changed.

Frequently asked questions

Why does my new hard drive show less space than the box says?

The box uses the decimal gigabyte (1,000,000,000 bytes), matching SI convention and how manufacturers have priced storage for decades. Your operating system typically computes free space in binary gibibytes (1,073,741,824 bytes) but mislabels the unit 'GB'. A '500 GB' drive genuinely has 500 billion bytes; it just reads as about 465.66 in the OS's mislabeled binary unit.

Is a kibibyte the same as a kilobyte?

No, though they are close: 1 KiB = 1,024 bytes and 1 KB = 1,000 bytes, a 2.4% difference. The gap widens at every step up, reaching about 10% by the terabyte/tebibyte level.

Which one should I use?

Use decimal units (KB/MB/GB/TB) for storage capacity, pricing and network transfer rates, matching manufacturer and SI convention. Use binary units (KiB/MiB/GiB/TiB) when you need the exact number of bytes a program or file system actually allocates, since memory and file systems are addressed in powers of two.

Do internet speeds use bits or bytes?

Internet and network speeds are almost always quoted in bits per second (Mbps, Gbps), while file sizes are quoted in bytes (MB, GB). A '100 Mbps' connection downloads at up to about 12.5 MB per second, since there are 8 bits in a byte.

How many bits are in a byte?

8 bits make 1 byte, the fixed ratio between the two smallest data units. It's also why a '100 Mbps' internet connection, quoted in bits, downloads at only about 12.5 MB per second: 100 ÷ 8 = 12.5.