What is the difference between GB and GiB?

A gigabyte (GB) is 1,000,000,000 bytes under the SI decimal standard. A gibibyte (GiB) is 1,073,741,824 bytes (1024³). GiB is about 7.4 percent larger, which is why a 1 TB drive shows as roughly 931 GiB in your OS.

Why do drive makers and operating systems disagree on size?

Storage manufacturers advertise capacity in decimal units (1 TB = 10¹² bytes), while many operating systems report in binary units but label them with decimal symbols. So a 1 TB drive looks like only about 0.909 TB to the OS.

How many bits are in a byte?

Eight. One byte equals 8 bits. File and storage sizes are usually quoted in bytes, while network and bandwidth rates are usually quoted in bits per second.

What are the IEC binary prefixes?

Kibi (KiB, 1024), mebi (MiB, 1024²), gibi (GiB, 1024³), tebi (TiB, 1024⁴) and pebi (PiB, 1024⁵). They were standardised by the IEC in 1998 to remove the ambiguity of using kilo, mega and giga for powers of 1024.

Does this tool run offline?

Yes. All conversions happen locally in your browser with JavaScript. No data is uploaded, logged or stored.

Data Storage Unit Reference

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Decimal and binary storage units side by side

The same word — kilobyte, megabyte, gigabyte — has meant two different things for decades. SI prefixes mean powers of 1000; the IEC binary prefixes (kibi, mebi, gibi) mean powers of 1024. This reference converts a size into every unit of both standards at once, so you can see exactly how big a difference it makes.

How it works

Every input is converted to a byte count first, then out to each unit. SI units divide by powers of 1000; IEC binary units divide by powers of 1024:

1 kB  = 1000 bytes        1 KiB = 1024 bytes
1 MB  = 1000² bytes       1 MiB = 1024² bytes
1 GB  = 1000³ bytes       1 GiB = 1024³ bytes
1 TB  = 1000⁴ bytes       1 TiB = 1024⁴ bytes

One byte is 8 bits, so the tool also shows the value in bits. Because everything routes through a single byte count, the decimal and binary columns stay exactly comparable.

Tips and notes

A “1 TB” drive holds 10¹² bytes, which your OS may report as about 931 GiB.
The gap grows with size: KiB/kB differ by 2.4 percent, but TiB/TB differ by 10 percent.
File sizes are in bytes; network speeds are in bits — divide bits by 8 to compare.
When precision matters, write the IEC prefix (GiB) to make the 1024 base explicit.