Know your units of measurement for data

[Yster21]

I didn't know where to post this, so I'm putting it here. I actually want it to be in the Fibre and ADSL sections, but can't post in both. Maybe a mod can move it to a more appropriate section.

Anyhow, since I have limited characters to catch and hold your attention, I'll use a cheap tactic and insult you to keep you interested. Do you think that there are 1,024 bytes in a kilobyte? Have you ever said "I have a 10mbit line"? If so, then I have taken *****s that are more informed than you.

Did it work? Do I have you? Hope so.

I'm a bit OCD, and it gives me a twitching eye when people start posting their internet speeds and messing up their units. There seems to be a hell of a lot of confusion over 'MBps' (or MB/s) and 'Mbps' (some mouth-breathers even type 'mbps'). I guess less than 10% (I just totally made that up) of the people who consider themselves knowledgeable in the field of IT even know what a MiB is, or why your 4TB hdd only shows up as 3.64TB in Windows.

SI scale prefixes
Let's start by talking about scale prefixes for SI units of measurement.

• Milli (always abbreviated as lowercase m) is 10[SUP]-3[/SUP]
• Kilo (always abbreviated as lowercase k, since K is Kelvin) is 10[SUP]3[/SUP]
• Mega (always abbreviated as capital M, otherwise you are referring to milli like an idiot) is 10[SUP]6[/SUP]
• Giga (G) is 10[SUP]9[/SUP]
• Tera (T) is 10[SUP]12[/SUP]

I can already hear you saying "ja ja, I know all that", except now I'll tell you that it doesn't matter what unit the prefix is coupled with, mega will always be 10[SUP]6[/SUP] times the value you are referring to. Stop frowning.

This is true: 1 kB = 1,000 bytes exactly. "No it isn't! It's 1,024 bytes you moron!" You're the moron. 1kB is 1,000 bytes, and 1 MB is 1,000,000 bytes exactly.

What you are referring to is when you make use of binary prefixes to indicate data size. They are defined as:

• 1 kibibyte (KiB) = 2[SUP]10[/SUP] = 1,024 bytes
• 1 mebibyte (MiB) = 2[SUP]20[/SUP] = 1,024[SUP]2[/SUP] = 1,048,576 bytes
• 1 gibibyte (GiB) = 2[SUP]30[/SUP] = 1,024[SUP]3[/SUP] = 1,073,741,824 bytes
• 1 tebibyte (TiB) = 2[SUP]40[/SUP] = 1,024[SUP]4[/SUP] = many bytes (you're not going to remember the actual value any more than I am)

More surprising is that this has been around since 1998, and was defined by the IEC in order to avoid confusion. I can see that it was a resounding success... Even Windows gets it wrong, and I am willing to bet that so does Linux and MacOS. What a pity: wrongness has been endorsed. Filezilla comes to mind as an application that gets it right.

So now, finally, you can do a little calculation and see that your 4TB drive is actually a full 4TB, or 3.63TiB. No one cheated you.

Data rates
For the final chapter, I shall get to the point I have been trying to make all along: stop being an idiot when you are talking about data rates. I see people complaining that they have a "100 mbps" line but when they download they get around "11 mbps only". My God people! That's because you have a 100 Mbps line and consequently you're getting around 11 MBps download rate.

We've already covered prefixes, so let's list the units:

• b is for bit. It can never ever ever mean byte. If you think it can, then please vacate the field of IT and go massage your anus (since that is where your brain is located)
• B is for byte. You apparently know that there are 8 bits to a byte, yet for some reason you mix b and B as if they're the same. I hate you and we can never be friends.
• The "p" and "/" both mean "per", though I daresay that we would "typically" write the bit rate with the 'p' and the data rate with the slash.

A lot of the articles, especially on this site, fall victim to the above. There is a massive difference between mbps, Mbps and MBps. There is no difference between MBps and MB/s, mbps and mb/s, or Mbps and Mb/s.

I typed 'mbps' as a trick! That's millibits per second. If you have a 10 mbps connection, then I have some bad news for you: downloading a 640 MB CD is going to take you over 16,000 years. On a 10 Mbps connection, it will take 8.5 minutes. Ahhh shift key, how you save our lives.

Ok, that's all I have. I can add one last little thing that some might have wondered about: why on my 100 Mbps connection, do my speed tests never go over 97 Mbps? That's because of overheads in the protocols lower down on the OSI model. Your interface is probably switching at perfectly 100 Mbps, but due to the fact that for each packet you download, some bytes of information are added for addressing, error checking and whatnot, you'll never get speedtest to give you the true result. Your data rate at Layer 1 will always be higher than what you measure up on higher layers.

If I made any errors, that was purely intentional and to test you.

 

[GreGorGy]

• Milli (always lowercase m) is 10[SUP]-3[/SUP]
• Kilo (always lowercase k, since K is Kelvin) is 10[SUP]3[/SUP]

But you used uppercase?

 

[Yster21]

But you used uppercase?

Don't be a troll

 

[GreGorGy]

Don't be a troll

Not trolling - communication is not clear - advising you adjust it.

 

[Yster21]

Not trolling - communication is not clear - advising you adjust it.

That's good, because trolling is my job! I cleared it up, though I figured it should be obvious that I was referring to the unit abbreviation, and not the name of the unit.

 

[etienne_marais]

Not trolling - communication is not clear - advising you adjust it.

The lower/upper case pertains to the abbreviation, not when writing it out as the first word of a sentence.

I thought you were joking.

 

[sam7606]

Oh so...
kB means Kilobyte
KB means Kelvinbyte (lol).
mB means millibyte
MB means Megabyte...
Got it...

 

[Yster21]

KB means Kelvinbyte (lol).\.

Kelvinbytes are for porn.

 

[animal531]

Where are the Petabytes+, what is this, 1999?

The kibi's etc are weird. They've been around a long time but people are really only starting to use them now. I suspect because 1000 is so close to 1k, we're just sort of shrugging and going close enough. The only place where it seems to bug people are on hdd sizes.

 

[Arthur]

Thanks, Yster21. You are a lone voice crying in the wilderness. As an erstwhile book publisher/editor I've been trying to get the planet to use the correct units and abbreviations since the mid-80s.

By the way, the etymologically-correct pronunciation of "giga" is "jigga", the "g" being as in "giant" (which is a cognate). Pronouncing it correctly will have 99.999% of humanity falling about in laughter at your apparent ignorance. Little do they know...

 

[access]

i did not learn the size of kilobyte or megabyte by studying a course, its what was displayed on the screen when there were no icons or pictures or things to make it look pretty.

so its been wrong since ive been using commodores of XT's or what ever?

its how much data would fit onto a floppy or a stiffy or himem or base memory, you had to work it out. those calculations were not wrong.


the KiB and MiB stuff just sounds like something marketing make up, because its easier for an end user to understand 1000 instead of 1024. or other way around what ever.

 

[access]

Thanks, Yster21. You are a lone voice crying in the wilderness. As an erstwhile book publisher/editor I've been trying to get the planet to use the correct units and abbreviations since the mid-80s.

By the way, the etymologically-correct pronunciation of "giga" is "jigga", the "g" being as in "giant" (which is a cognate). Pronouncing it correctly will have 99.999% of humanity falling about in laughter at your apparent ignorance. Little do they know...

oh, so it has been wrong since the 80's ...lol

 

[Arthur]

the KiB and MiB stuff just sounds like something marketing make up, because its easier for an end user to understand 1000 instead of 1024. or other way around what ever.

Exactly the reverse. KiB and MiB are the correct terms consistent with SI definitions. Tech-heads, nerds, engineers and other tech people concerned with accuracy in communication know that. KB, Kb, etc are creations by people who never paid much attention to getting details correct, like Marketing types.

 

[Arthur]

oh, so it has been wrong since the 80's ...lol

Erros have as way of embedding themselves in the culture, especially one so narrow as the IT industry. Do some research and you'll find "jigga" was standard for years. It's even used in films like Back to the Future.

 

[access]

Erros have as way of embedding themselves in the culture, especially one so narrow as the IT industry. Do some research and you'll find "jigga" was standard for years. It's even used in films like Back to the Future.

yeah ive wondered about that, i thought that only relates to power/electricity, like kilojoules. or maybe one of those american english ways of pronouncing things.

interesting.


thinking back to the first year of studying, the lecturer also explained it wrong then, even with his excitement for nibbles

 

[Jet-Fighter7700]

yeah ive wondered about that, i thought that only relates to power/electricity, like kilojoules. or maybe one of those american english ways of pronouncing things.

interesting.


thinking back to the first year of studying, the lecturer also explained it wrong then, even with his excitement for nibbles

but even in back to the future where the subtitles are wrong,
1.12 jiggawatt of electricity, not gigawatt

the subtitles are wrong then, but I suppose its like a silent g, like knife...
so yes its all wrong, but people just continue it,

 

[Jet-Fighter7700]

This is true: 1 kB = 1,000 bytes exactly. "No it isn't! It's 1,024 bytes you moron!" You're the moron. 1kB is 1,000 bytes, and 1 MB is 1,000,000 bytes exactly.

.

actually the way it was explained to me is the MB rounded down to 1000, is due to our numbering system that only allows everything to be base 10,
as we have 10 fingers and 10 toes.... ( those of us mutants need not worry....)

so its rounded down for "convienience"

computers can only count in base 2 IE, one and zero, and those are the only 2 numbers they can use to make any number imaginable,

so how do we get to MB, its actually 1024 as 8 bits IE ones and zeros in a configuration of 8 added up will equal 1024 if you counted all the numbers individually,
we round it down, due to our base 10 instinct, so thats actually why its 1000 MB, and we tend to think that way...

BTW: you never talked about nibbles ....
or octal or hexa...

 

[Yster21]

actually the way it was explained to me is the MB rounded down to 1000, is due to our numbering system that only allows everything to be base 10,
as we have 10 fingers and 10 toes.... ( those of us mutants need not worry....)

so its rounded down for "convienience"

My point was that Mega is 10[SUP]6[/SUP], regardless of what follows. Whoever explained it to you, seems to be confused. Science and engineering don't care about human convenience. If you write a technical report, you "should" get hammered on getting your units confused, and a stern lecture from whoever had to review it.

I actually wrote this post after another post in the fibre section got me all worked up. Some poor soul could not understand why his "100 mbps" line was only giving him "11 mbps". Only after he posted a screenshot, could people tell him "your 100 Mbps line should only give you 11 MBps!". I think he's still confused.

computers can only count in base 2 IE, one and zero, and those are the only 2 numbers they can use to make any number imaginable,

so how do we get to MB, its actually 1024 as 8 bits IE ones and zeros in a configuration of 8 added up will equal 1024 if you counted all the numbers individually,
we round it down, due to our base 10 instinct, so thats actually why its 1000 MB, and we tend to think that way...

What? There is no rounding of anything. Each bit and byte is accounted for. When working up to megabyte level, you can still loosely compare 1 MiB to 1 MB, but at terabyte level the discrepancy is already starting to show, since as my example showed, 4TB = 3.63TiB.

BTW: you never talked about nibbles ....
or octal or hexa...

What do you need me to say about it?

 

[Thor]

give this man a beer!!