The packaging says 500 gigabytes of storage, yet when that new hard drive is plugged into a computer it only shows up as having 465 gigabytes available.
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Where’s the rest of the space, bewildered buyers might ask. The answer is both simple and complicated: The difference is based on different calculation methods employed by manufacturers of storage media and operating system developers.
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The bigger the storage, the more the difference becomes obvious — as much as ten percent for a one terabyte hard drive. And to make matters worse, another small portion of the hard drive is lost when the device is formatted.
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Many consumers presume that 1,000 bytes is a kilobyte, and that 1,000 kilobytes are a megabyte. After all, 1,000 metres make one kilometre, and 1,000 grams make one kilogram. Things are calculated differently in the world of IT, says Gerhard Henninger, an expert in multimedia standards at the German Commission for Electrical, Electronic, Information Technologies (DKE) in Frankfurt.
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Computers work on a base two, not a base ten system. Properly speaking, that means that a kilobyte is not 1,000, but rather 1,024 bytes.
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Just as engine makers typically round up displacement sizes, many producers of storage media — hard drives, flash drives, DVDs, Blu-Ray discs, and so on — make their products out to be bigger than they really are. They do so by listing the size as a factor of ten instead of a factor of two. That means making 1000 bytes into a kilobyte.
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Yet nothing they say will convince an actual computer that 1024 bytes are a kilobyte. The operating system nevertheless requires more kilobytes to produce that gigabyte or terabyte figure quoted by the manufacturer.
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Because the difference between 1000 and 1024 bytes is only 2.4 percent, the difference is not that noticeable at the kilobyte level. Yet at…