Data Storage Converter
Bytes to terabytes, with the 1000 and 1024 systems kept separate.
A 1 TB drive shows up as 931 GB, a 25 Mbps connection downloads at 3 MB per second, and a 700 MB file will not fit on a 700 MB disc. None of these are faults. They are all the same disagreement: whether a kilobyte is 1000 bytes or 1024. This converter makes you choose which system you mean instead of quietly picking one.
| Unit | Symbol | Value |
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How it works
Choose a system
Decimal for drives and networks, binary for what your operating system reports.
Pick the units
Bytes through petabytes, in both families.
Read the table
The same quantity is shown in every unit of the chosen system.
Why your 1 TB drive shows 931 GB
The drive is not lying and neither is the operating system — they are using different definitions. Manufacturers use the decimal prefixes as the SI standard defines them, so one terabyte is 1012 bytes, a round number in the units the industry sells in. Windows and most operating systems divide by 1024 at each step but keep the label "GB", so the same 1012 bytes gets reported as 931.32.
The gap widens as the units grow, because it compounds. At the kilobyte it is 2.4%; at the megabyte 4.9%; at the gigabyte 7.4%; at the terabyte 9.1%. That last figure is exactly the missing 69 GB, and it is why the discrepancy feels like it appeared recently — it was barely visible when drives were measured in megabytes.
The standards body resolved this in 1998 by defining separate binary prefixes: kibi, mebi, gibi, tebi, with the symbols KiB, MiB, GiB, TiB. macOS and Linux distributions largely adopted the decimal meaning for the plain prefixes; Windows still reports binary quantities with decimal labels. This converter keeps the two families in separate tabs, because mixing them is the entire problem.
Bits, bytes and the other factor of eight
Network speeds are quoted in bits per second, storage in bytes, and a byte is eight bits. A 100 Mbps connection therefore transfers at most 12.5 megabytes per second, and a "300 Mbps" plan will never copy a file faster than about 37 MB/s. The distinction hides in the capitalisation — Mb is megabits, MB is megabytes — which is a great deal of weight for one letter to carry.
Protocol overhead takes another cut on top. TCP/IP headers, retransmissions and encryption typically account for a few percent, so real throughput lands slightly below the arithmetic maximum even on an otherwise idle line. A rough working figure: divide the advertised megabits by ten rather than eight, and the answer will be close.
The byte itself was not always eight bits. Early machines used six, seven or nine depending on the character set they were built around, and the standards still say "octet" when they mean exactly eight to avoid the ambiguity. Every system in current use settled on eight decades ago, so the conversions here treat a byte as eight bits without qualification.