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HI

If we purchase a 20Mb leased line and we are downloading at 20Mb all month.

How much will we be able to download each month in total (on average)?

Thanks

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closed as not a real question by Scott Pack, Ben Pilbrow, Iain, Ward, RobM Mar 10 '11 at 8:15

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"20MB"? Usually connections are measured in mega bits per second, but "B" usually refers to bytes, whereas "b" refers to bits. It's probably worth clarifying this. en.wikipedia.org/wiki/Byte#Unit_symbol –  Bryan Mar 9 '11 at 16:08
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It's amusing to watch how many people (myself included) spring on a question like this, which is both technically simple and technically incorrect. 6 replies and a good bunch of comments already! –  Coops Mar 9 '11 at 16:13
    
Its Mb sorry for the confusion. Also we have a 100Mb pipe and our monthly limit it 20Mb on average- 95 percentile. –  Adam Mar 9 '11 at 16:43
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7 Answers 7

Presuming you mean "20 megabytes per second"...

20MB/s constant for 30 days is around 50TB

If you mean "20 megabits per second", that would be about 6TB.

Normally you describe connection speed in megabits (Mb) rather than megabytes (MB).

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If you have no latency (eg: you are not in the real world physics of moving bits via light or electricity) then there are 2592000 seconds in 30 days, multiply by 20 megabits per second and you get 6.18 terabytes total. With physical latency and network traffic, really no way to know the real maximum.

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20 * 1024 * 1024 * 60 * 60 * 24 * 30 = 54,358,179,840,000 bits = 6.17 Terabytes. (Insert usual disclaimer about real-world vs theoretical limits, here.)

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question actually said MB not Mb (but I presume he means Mb!) –  Coops Mar 9 '11 at 16:09
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Yeah, I was assuming Mbits/s, since that's how almost all connectivity is sold. (Also, a 160Mbits/s connection would be odd.) –  SmallClanger Mar 9 '11 at 16:36
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20 mbit is:

  • about 2 megabytes per second (some overhead).
  • about 7200 megabytes per hour
  • about 168 gigabytes per day (rounded)
  • about 5050 gigabytes per month.
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MB/s or Mb/s?

If it is MB/s then: 20MB/s * 60s/m * 60m/h * 24h/d * 30d/m = 51840000 MB (50625 GB)

Since I think this is unrealistic I'm assuming you have a 20 Mb/s connection rate so:

51840000 Mb % 8b/B = 6480000 MB % 1024 MB/GB = 6328.125 GB

(Theoretical limits at 100% usage of course ... real world doesn't apply here)

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Here is a calculator.

It depends on what you mean by MB = megabytes or megabits per second.

It could be either 54 Terabytes or 6.5 Terabytes worth of data per month, depending on what you mean. ( My guess the latter, cause otherwise you've got a very nice pipe, and I envy you :-)

This calculation assumes, you are utilizing it at full capacity 100 % of time, without any interruptions, no latency, and your pipes run on superconductors that are not susceptible to any interference.

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About 6.28 Tera a bytes (based on a 30 day month).

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6280 mgeabtyes? In a month? Get your maths straight. –  TomTom Mar 9 '11 at 16:03
    
20MB/s constant for 30 days is around 50TB no? –  Coops Mar 9 '11 at 16:05
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Adam's question isn't specific about the download rate, but with my 8Mbps connection at home, I can easily hit over 40GB per month without really trying. –  Bryan Mar 9 '11 at 16:14
    
mrdenny isn't normally wrong, so I'm going to assume that this is just a typo and he meant 6.28Tb –  Mark Henderson Mar 11 '11 at 0:20
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Apparently when you don't divide by 1024 enough times you look a little silly. :) –  mrdenny Mar 11 '11 at 6:51
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