MB and GB are decimal units, while MiB and GiB are binary units. One GB is 1,000,000,000 bytes and one GiB is 1,073,741,824 bytes, so a drive advertised as 1 TB decimal appears as about 931 GiB when software reports binary-sized units. The byte count has not changed.
Why is a 1 TB drive smaller in my computer?
A drive marked 1 TB contains 1,000,000,000,000 bytes when the label uses decimal prefixes. Divide that byte count by 1,073,741,824 bytes per GiB: the result is about 931.3 GiB. If an operating system displays “931 GB” but uses binary-sized units in the interface, the apparent shortfall is a naming convention, not 69 billion bytes missing from the drive.
What is the difference between MB and MiB?
Find the unit symbol and, when possible, the byte count. Use decimal factors for kB, MB, GB, and TB: powers of 1,000. Use binary factors for KiB, MiB, GiB, and TiB: powers of 1,024. The data-storage converter uses decimal GB and MB in its stated example; do not feed it a GiB value as though the symbols were interchangeable.
What is the difference between GB and GiB?
A byte is 8 bits. A megabyte, MB, is 10⁶ bytes; a mebibyte, MiB, is 2²⁰ bytes. A gigabyte, GB, is 10⁹ bytes; a gibibyte, GiB, is 2³⁰ bytes. The added “i” in MiB and GiB identifies binary multiples and prevents the historical ambiguity of calling 1,024-based quantities MB or GB.
How do decimal and binary storage prefixes convert?
Do not convert 1 TB to 1,000 GiB; it is 1,000 decimal GB but about 931 GiB. Do not call MB and MiB identical at large sizes. Do not blame the prefix difference for all missing usable space: formatting, recovery partitions, filesystem metadata, and decimal display can also change what is available. Do not confuse bits, b, with bytes, B.
What storage differences are not caused by prefixes?
This guide explains storage-unit labels, not available capacity after installation. It cannot determine a device’s health, filesystem overhead, cloud quota policy, transfer speed, or backup requirement. Read the device and operating-system documentation when a particular system reports capacity differently.
Source for the external fact
NIST’s binary-prefix definitions state that 1 MiB is 2²⁰ bytes, 1 GiB is 2³⁰ bytes, and 1 GB is 10⁹ bytes; IEC standardises binary multiples for information science and technology in IEC 80000-13.
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