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Data Storage Converter

Convert between bits, bytes, kilobytes, megabytes, gigabytes, terabytes and petabytes, and their binary versions KiB, MiB, GiB, TiB and PiB.

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Convert a data size

How to use the converter

Type a size in the Value box, choose the unit you have and the unit you want, then press Convert. The swap button flips the two units. A table below the result shows the same amount in all fifteen units.

The converter starts on gigabytes (GB) to gibibytes (GiB), the pair that causes the most confusion.

Bits and bytes

A bit is a single 0 or 1. A byte is 8 bits. Network speeds are usually given in bits per second (Mbit/s), while file and disk sizes are given in bytes. That is why a 100 Mbit/s connection moves at most 12.5 megabytes per second: 100 ÷ 8 = 12.5.

Decimal and binary units

There are two families of prefixes:

  • Decimal (SI) units use powers of 1,000: 1 kB = 1,000 bytes, 1 MB = 1,000,000 bytes, 1 GB = 10^9 bytes, 1 TB = 10^12 bytes, 1 PB = 10^15 bytes.
  • Binary (IEC) units use powers of 1,024: 1 KiB = 1,024 bytes, 1 MiB = 1,048,576 bytes, 1 GiB = 2^30 = 1,073,741,824 bytes, 1 TiB = 2^40 bytes, 1 PiB = 2^50 bytes.

The binary names (kibi, mebi, gibi, tebi, pebi) were introduced so that each prefix has only one meaning. In everyday use, however, the binary amounts are still often labelled kB, MB or GB.

Why a 1 TB drive shows about 931 GB

Drive makers use decimal units, so a 1 TB drive holds 1,000,000,000,000 bytes. Some operating systems divide the byte count by 1,024 three times but still write "GB". The result is:

1,000,000,000,000 ÷ 1,073,741,824 ≈ 931.32

No space is missing; it is the same number of bytes measured with a different unit. Correctly labelled, the drive holds about 931.32 GiB or 0.909 TiB. The gap grows with each prefix: a gigabyte is about 7% smaller than a gibibyte, and a terabyte about 9% smaller than a tebibyte.

Worked example

To convert 1 GB to GiB: 1 GB = 1,000,000,000 bytes, and 1,000,000,000 ÷ 1,073,741,824 ≈ 0.931323 GiB. In the other direction, 1 GiB = 1.073741824 GB exactly.

Good to know

  • Results are shown with up to six decimal places; very small values are written in scientific notation.
  • Sizes cannot be negative. Zero is accepted.
  • Lowercase b usually means bits and uppercase B means bytes, so Mb and MB differ by a factor of 8. This converter writes bit units as kbit, Mbit and Gbit to avoid that mix-up.

Frequently asked questions

Is a kilobyte 1,000 or 1,024 bytes?

By the SI standard a kilobyte (kB) is 1,000 bytes, and 1,024 bytes is a kibibyte (KiB). Older software and some operating systems still call 1,024 bytes a kilobyte, so check which meaning a program uses.

Why does my new hard drive show less space than advertised?

The box uses decimal units (1 TB = 10^12 bytes), while some operating systems report sizes in binary units but label them GB. 10^12 bytes is about 931.32 GiB, so a 1 TB drive appears as roughly 931 GB. Formatting and preinstalled files take a little more.

How many megabytes per second is a 100 Mbit/s connection?

Divide by 8, because a byte has 8 bits: 100 Mbit/s is 12.5 MB/s at most. Real downloads are a bit slower because of protocol overhead.

What is the difference between GB and GiB?

A gigabyte (GB) is 1,000,000,000 bytes and a gibibyte (GiB) is 1,073,741,824 bytes. One GiB is about 1.074 GB, and one GB is about 0.931 GiB.