Digital storage and data transfer speeds are measured using standard unit prefixes — kilo, mega, giga, tera, and beyond — but two competing measurement systems, SI and binary, produce values that diverge significantly at higher scales. Understanding both systems is essential for accurately interpreting storage capacities and network speeds in real-world IT environments.
Kilobytes & Megabytes Explained
My guess is that many of you already know or have encountered what a kilobyte is or what a megabyte is, and have some general idea of the concept of them. But what is it specifically, and more importantly, is there any variation with this? The answer to that is yes.
A kilo stands for 1,000. So if I have a kilobit, that's 1,000 bits. If I have a kilobyte, it's 1,000 bytes. Same thing with mega: if I have a megabit, then it's a million bits; if I have a megabyte, then it's a million bytes. Same thing with giga, which stands for billion, and tera, which is trillion, and so on and so forth.
Here's another way to look at that. Let's say I had a terabyte of information. That would be a trillion bytes, or it would be a billion kilobytes, or it would be a million megabytes, or a thousand gigabytes.
So how do we represent this? If we're talking about speeds, we just add a bps to the end of whatever letter it is. Notice the K is lower case and the rest of these are upper case, so mega, giga, tera and peta here. If it was storage, same thing, except it's just represented by a B rather than the bps over here. And it's usually big B because it's storage, so we're talking about bytes usually.
Let's actually apply this. What does this look like? For the first one here, what we have is 8 terabytes, so that would be 8 trillion. If I were to write this out, it'd be 8, and this would be thousand, this would be million, this would be billion, and then trillion. And it's a byte, so we're going to say byte right here. That's how we would come up with this.
I can do the next one as well: 64, and this would be thousand and this would be million, and this is a megabyte. So 64 million bytes is what this is.
What you can do is go and figure out the rest of these, and then we'll come together and see what we come up with. The answers to these are right here, so you can check your answers to see how close you got. Hopefully you caught that this was a little b, as well as all these transmission speeds. These are some of the transmission speeds and some of the data rates that you would actually see out there on a lot of our ethernet connections.
For the most part it really is just that simple, and for most of what we're doing, this is simple enough. However, if we're getting really granular on how we're measuring things, there is one concern that comes up, and that's that not everybody measures this all the same.
What I've just gone over is the international system of units, and that's pretty standard out there for measuring not just computer stuff but all sorts of things. So we use this system for measuring computer stuff as well. But it's not the only way that we measure things. There's also this binary prefix here, and we measure it in 1024 instead. So a kilo is. A giga is this number right here. A tera and a peta. We can see a difference with this, and that's because instead of using 1,000 to whatever power, we're using 1024 to whatever power.
Why this makes a difference is because on a small scale it really doesn't make much of a difference. If we're talking about kilos, 1,000 versus 1,024 is just a 2.4% difference. But as we work our way up, since we're using 1024 rather than 1,000, now we see at the peta range it's a 12% difference, and that's fairly significant.
There's a lot of confusion out there when it comes to these units, and a lot of misinformation that's out there as well. You'll see much of this measured in SI and much of it measured in binary prefixes. To help try to standardize this, in 1998 the IEC tried to say, okay, this is what you should do. If you're using the SI form of measuring this, you can call it kilobytes, megabytes, gigabytes, terabytes and so on and so forth, and you can use the standard measurement. However, if you're using the binary prefix form of this, we should call it a kibibyte, a megbibyte, a gigbibyte, a tebibyte. These are how you should specify it, with a little i slipped in there, so that people know the difference and can understand the difference.
However, a lot of people don't follow these rules, so even though they're using binary prefixes, they still represent their data as if it's an SI type of measurement here. So the biggest thing is that for the most part you're safe using the SI, but if you want to get really granular, then you'll have to look into the specific technology that you're using and make sure that you're calculating things correctly.
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