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How many gigabytes does your hard drive or SSD hold? Are you sure about that?

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We've already discussed how over-provisioning and file system overhead often mean that the usable

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capacity of your drives is less than what's advertised, and you can check out this video

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to learn more. But it turns out there's another way that you can be easily fooled,

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the fact that the term Gigabyte itself can be ambiguous.

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Many of us think of a Gigabyte as exactly 1 billion bytes,

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however, it's a commonly accepted practice in the industry to instead use Gigabyte to mean

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this many bytes. If you look closely, that's a difference of about 74 megabytes,

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which is not an insignificant gap. So why does the industry have to make things so complicated?

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To get the answers, we have to look way back to the early days of modern computing.

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As early as the 1960s, binary addressing was already the standard for a working memory or RAM.

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You see, when a computer puts something into memory, that data is assigned to a particular

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address so the system can recall where it's stored. Binary addressing means that each

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memory address is expressed in binary digits, that is ones and zeros. So for example, if you have a

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10-bit address, there are two to the 10th power or 1024 possible addresses, not exactly 1000.

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It therefore became convenient to refer to 1024 bits as a kilo bit, or the same number of bytes

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as a kilo byte, even though those uses didn't strictly line up with the meaning of the kilo

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prefix as it's used in fields outside of computer science. We've also seen this at times with mass

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storage devices. During the 1980s, when the IBM PC platform was becoming popular, the industry

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needed to decide on a standard sector size. And if you didn't know, a sector is the smallest

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amount of data that can be stored at one time on a drive. The powers that be settled on making 512

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bytes the default size for one sector. And if you put two sectors together, you have 1024 bytes,

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which matched the binary addressing definition of kilo byte we discussed earlier.

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Even today, when we're using much larger drive sizes, sectors are still defined by sizes and

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powers of two, with the sector today usually coming in at 4096 bytes. However, the storage

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industry today typically uses the more common exactly one billion bytes definition of Gigabyte,

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since this definition allows drive makers to put larger capacities on their packaging and claim

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slightly faster speeds on their spec sheets. But wouldn't it be nice to know exactly what you're

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getting when you go out and buy a drive or memory card? Thankfully, more precise terms were published

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in 1999 with words like megabyte and gibby byte that unambiguously refer to units that are powers

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of two with the by or bi in the middle standing for binary. If you want to write that out as

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abbreviation, sticking a lowercase i between the capital G and the capital B is the correct way to

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do it. However, this obviously hasn't solved the problem completely. The more common words like

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megabyte and Gigabyte can refer to data units in either system, and the words with by or b in

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the middle haven't gained a whole lot of traction outside of tech circles. In fact, there have even

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been lawsuits over how these terms are used, with customers claiming that they got less storage than

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they paid for in certain circumstances. And as storage continues to grow and grow, this could

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become a more significant issue. For example, there's about a 125 terabyte difference between

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a petabyte and a pebby byte, but maybe we'll just constantly be storing such large files on

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our devices that these differences won't matter very much. Personally, I'm looking forward to

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sharing food photos on Instagram in 16k with encoded smell data. So thanks for watching guys,

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if you liked this video, give us a like, hey, hit subscribe, why not? And be sure to hit us up in

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the comments section with your suggestions or topics that we should cover in the future.