Data storage converter
Bits, bytes, KB, MB, GB, TB and PB converted in real time, in both the decimal system (×1000) and the binary system (×1024) used by operating systems.
Enter an amount to see every conversion.
| Decimal (×1000) | Binary (×1024) | ||
|---|---|---|---|
| bit | byte | ||
| KB | KiB | ||
| MB | MiB | ||
| GB | GiB | ||
| TB | TiB | ||
| PB | PiB |
Why does a 1 TB drive show "only" 931 GB?
It's not a defect and nobody is cheating you, it's a units issue. Hard drive and SSD manufacturers use the decimal system, where 1 TB = 1,000,000,000,000 bytes. Windows, however, measures space with the binary system (a Windows "GB" is really a gibibyte, i.e. 1,073,741,824 bytes): divide a trillion bytes by that figure and you get about 931 GiB. All the space is there, only the ruler used to measure it changes. macOS and Linux, on the other hand, have shown decimal GB since 2009, matching the number on the box.
The right names exist, and nobody uses them
To remove the ambiguity between the two ways of counting, separate names have existed since 1998: kilobyte, megabyte and gigabyte (KB, MB, GB) mean a thousand, while kibibyte, mebibyte and gibibyte (KiB, MiB, GiB) mean 1024. Linux uses them, as do some technical programs and the specifications; almost nobody else does, and Windows still writes «GB» when it's counting in gibibytes. That's why the same thing has two numbers and it looks as though somebody is getting it wrong.
Where one is used and where the other
For a thousand: disk and memory-stick makers, phone operators, the Mac, Android phones. For 1024: RAM (which is built in powers of two, so there it's the only sensible way), Windows, and most programs that show a file's size.
The difference grows with size: it's 2.4% on kilobytes, 7% on gigabytes, 10% on terabytes and almost 13% on petabytes. That's why the results table puts the two columns side by side: on the left it counts by a thousand, on the right by 1024.
Bits vs. bytes: watch out for internet plans
A byte is made of 8 bits, and the difference trips up plenty of people shopping for an internet plan: "gigabit" fiber runs at 1 gigabit per second, which is about 125 megabytes per second. A 4 GB movie, under ideal conditions, therefore downloads in roughly half a minute, not in 4. Rule of thumb: network speeds are quoted in bits (Mbps, Gbps), file sizes in bytes (MB, GB). This converter puts them side by side so you never mix them up.
The byte is written with a capital B, the bit with a lowercase b: «100 Mb/s» and «100 MB/s» are two different speeds, and the second is eight times the first.
Nearby tools
To work out how long a file takes to download there is Download time, and for a video's size before export Video bitrate and size. If a file needs slimming down, the pages are Compress image, Compress PDF and Compress an Office file.