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Data Storage Converter (Decimal and Binary)

Convert digital storage between bits, bytes and the decimal (kB, MB, GB, TB) and binary (KiB, MiB, GiB, TiB) prefixes. Both families are listed separately so a drive label and an operating system figure can be reconciled.

By Adzita Editorial Team · Updated 2026-11-03 · How we build and check our tools

Decimal prefixes versus binary prefixes

Two systems share the same abbreviations in everyday speech, and that is the source of nearly all confusion. SI prefixes are powers of 1,000: 1 kB = 1,000 bytes, 1 MB = 1,000,000 bytes, 1 GB = 10⁹ bytes and 1 TB = 10¹² bytes. Computer memory, however, naturally comes in powers of 2, so 1,024 bytes was long called a kilobyte.

To remove the ambiguity, the IEC introduced binary prefixes in 1998: 1 KiB = 1,024 bytes, 1 MiB = 1,048,576 bytes, 1 GiB = 1,073,741,824 bytes and 1 TiB = 1,099,511,627,776 bytes. This converter keeps the two families apart, so you always know which one a result belongs to. One byte is eight bits.

Why a new drive shows less space

Storage makers label capacity in decimal units. A "1 TB" drive holds 1,000,000,000,000 bytes. Some operating systems divide by binary powers but still print "GB", so the same drive appears as about 931 GB. Nothing is missing: 10¹² ÷ 2³⁰ is 931.32, and the unit label is the only thing that differs. File systems also reserve a small amount for their own structures, which removes a little more.

Label	Bytes	Shown in GiB
256 GB	256,000,000,000	238.4
500 GB	500,000,000,000	465.7
1 TB	1,000,000,000,000	931.3
2 TB	2,000,000,000,000	1,862.6

Bits and bytes in speeds

Capacity is quoted in bytes (capital B) and network speed in bits (lowercase b). A connection rated at 100 Mbit/s moves at most 12.5 MB of data per second, since 100 ÷ 8 = 12.5. Downloading a 1 GB file at that speed takes at least 80 seconds, before any overhead. Always check the case of the letter: Mb is megabit, MB is megabyte.

Practical tips

Use decimal units when comparing product capacities, and binary units when working out how much a file system will show.
The prefix k is lowercase in SI (kB), while K was widely used for 1,024 in older documents.
Cloud plans, camera cards and phones usually advertise decimal gigabytes, so allow for the system software that takes part of the space.

Results are shown to about six significant digits. For exact byte counts, convert to bytes and read the full figure.

A short example shows the scale of the gap. At the kilobyte level the difference between 1,000 and 1,024 is 2.4%. At gigabytes it grows to 7.4%, and at terabytes to 10%, which is why the mismatch is more noticeable on large drives than on small ones.

Worked example

A drive is sold as 500 GB (decimal). How much is that in gibibytes, the way many operating systems count?

Inputs

Value	500
From	Gigabytes (decimal) (GB)
To	Gibibytes (binary) (GiB)

Result

465.661287 GiB

500 GB = 465.661287 GiB

Bits (bit)	4,000,000,000,000
Bytes (B)	500,000,000,000
Kilobytes (decimal) (kB)	500,000,000
Megabytes (decimal) (MB)	500,000
Terabytes (decimal) (TB)	0.5
Petabytes (decimal) (PB)	0.0005
Kibibytes (binary) (KiB)	488,281,250
Mebibytes (binary) (MiB)	476,837.1582
Tebibytes (binary) (TiB)	0.4547474
Pebibytes (binary) (PiB)	0.0004440892

Factors are exact definitions where one exists; results are shown to about six significant digits.

Accuracy note: Factors use the standard definitions stated on this page. Results are rounded for display; for engineering or legal work use the full-precision factors.

Frequently asked questions

How many MB are in a GB?

In decimal units, 1 GB is 1,000 MB. In binary units, 1 GiB is 1,024 MiB. This converter lists both.

Why does a 1 TB drive show as 931 GB?

The drive holds 10^12 bytes, and software that divides by 2^30 and calls the result GB reports about 931.3. The capacity is the same; only the unit differs.

How many bits are in a byte?

A byte contains eight bits, so 1 byte equals 8 bits and 1 bit equals 0.125 bytes.

What is a gibibyte?

A gibibyte (GiB) is 2^30 bytes, or 1,073,741,824 bytes. It is the binary counterpart of the decimal gigabyte.

Is Mbps the same as MBps?

No. Mbps means megabits per second, while MBps means megabytes per second. One megabyte per second is eight megabits per second.

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More conversion references

For data storage conversion tables beyond this tool, see PakMath data storage conversion tables. PakMath is a sister project of Adzita.