Storage Unit Converter (GB, GiB, Mbit)

Two systems behind the same word

"A gigabyte" can mean two different amounts depending on who's saying it. In the decimal (SI) system — used by drive manufacturers, internet providers, and most technical specs — each prefix multiplies by 1,000: a kilobyte is 1,000 bytes and a gigabyte is 1,000³ = 1,000,000,000 bytes. In the binary system — used by RAM and much of the software world — each prefix multiplies by 1,024 (2¹⁰): a "kilobyte" is 1,024 bytes and a "gigabyte" is 1,024³ = 1,073,741,824 bytes.

To end the ambiguity, the IEC defined dedicated binary prefixes in 1998: kibi, mebi, gibi, tebi (KiB, MiB, GiB, TiB). So GB should always mean 10⁹ bytes and GiB, 2³⁰ bytes. The trouble is that plenty of software still writes "GB" while computing in GiB — which is where the most common storage question comes from: why does a 1 TB drive show up as 931 GB?

Unit table

The difference column shows how much smaller a decimal capacity looks once it's expressed in binary units. The gap widens with each prefix: at kilobytes you barely notice, but at terabytes it's nearly 10%.

Network speeds are measured in bits, not bytes, and always with decimal prefixes: 1 Mbit/s is 1,000,000 bits per second. Since a byte has 8 bits, divide by 8 to get bytes per second.

How to use the converter

• Enter an amount (with a decimal point or comma) and pick its unit: the converter shows the exact equivalent in every decimal, binary, and bit unit at once. It uses exact arithmetic, with no floating-point rounding errors, so 1 TB comes out as exactly 931.322574615478515625 GiB (the table shows up to six decimals).
• If the unit is decimal, a note shows how Windows would display that capacity: the binary figure, but with the decimal label File Explorer uses.
• The transfer time block works out how long that much data takes to move at a given speed — say, over a 300 Mbit/s connection or to a disk that copies at 150 MB/s.
• The amount and unit are kept in the URL, so a link like 4 TB opens the converter with those values.

Reference capacities

Windows truncates instead of rounding, which is why 1.82 TiB shows up as "1.81 TB." On top of that gap comes the space taken by the file system, recovery partitions, and — on Linux with ext4 — the 5% reserved for root by default. All of it, with examples from each operating system, is covered in GB vs. GiB: Why a 1 TB Drive Shows 931 GB.

Connection speeds in bytes per second

These are theoretical maximums: TCP, IP, and Ethernet headers eat roughly 5% of the bandwidth, and real-world speed also depends on the server at the other end, the Wi-Fi network, and the destination disk. In practice, a 1 Gbit/s connection rarely downloads faster than 110–118 MB/s.

Where each system shows up

Privacy

All conversions are calculated in your browser. Only the amount and unit are kept in the URL so you can share the result; nothing is sent to a server.