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We're diagnosing a speed problem between our shenzhen office and our asset management server. It seems stupid, but I need to get the data in the same format.

How do i convert the MBps that isp's quote, and that tools like speedtest.net spit out, and convert that the k/s my management are used to seeing on firefox and ie?

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Are you sure your ISP quotes MB and not Mb? The difference is a factor of 8 and I would be shocked to see it quoted in MB over Mb. –  MDMarra Dec 15 '09 at 15:59
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5 Answers 5

up vote 3 down vote accepted

The google suggestion is a good one. This "old way" is useful in generic unit conversions because you can change the time too. Make sure to set up your units so that they cancel out.

10 megabits per second: 10 Mb/s
1 megabyte is 8 megabits: 1 MB/8 Mb
1024 kilobytes is 1 megabyte: 1024 kB/1 MB

Write it out this way, cancel out the units, and you're left with 1280 kB per second.

   10 Mb       1 MB       1024 kB      1280 kB
  -------  x  ------  x  ---------  =  -------
     s         8 Mb        1 MB           s

You can change the time unit in the same way.

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Bits and Bytes:
The 8 bits to one byte is very important as has been mentioned, so make sure you get this right. Capital B generally means bytes, whereas lowercase b is bits, but this is not always the case. So really, you just need to ask the ISP if you are talking bits or bytes. From my experience, bandwidth from ISPs is almost always bits.

Google Can Do It!:
If you want to be nice and lazy, just Google the following:

10 megabytes in kilobytes

Which Returns:

10 megabytes = 10 240 kilobytes

because Google calculator will do this for you, you can change bytes to bits in either or both to suit your needs. :-)

Other Things:
There is upload speed and download speed, half-duplex and full-duplex, and also very important in choosing an ISP is latency. I recommend you go and research these topics a little bit and grill the ISP tech-sales person about them. If they are good sales people, you can also just say "I heard latency is important, what is the deal with that?". But the more you know, the better you can tell if you are getting quality honest answers.

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Well lets just drop the "ps" from MBps and /s from k/s since they are both referring to "per second". This would leave us with MB and k. Now you just need to know if it is KB or Kb (bits vs Bytes) and google can do the rest. Go to google.com and type in "XMB to KB" or "XMB to Kb" where X is the number and you will get the conversion you need. Slap the /s or ps back on there and you have the rate you are looking for.

From there you can probably figure out the "formula"...

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the 'k' for kilo is actually always written lower-case since K is already used for degrees Kelvin. –  MDMarra Dec 15 '09 at 15:55
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+1 Sorry, I stole your google answer without realizing it... –  Kyle Brandt Dec 15 '09 at 16:21
    
i still haven't gotten the good looks down with my answers so you win there. –  EasyEcho Dec 15 '09 at 17:55
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Divide by 8 (to convert megaBITS to megaBYTES per second) then multiply by 1,024 (to convert MEGAbytes to KILObytes).

Use caution when comparing actuals to ISP quoted speeds, since ISP quotes are almost always theoretical maximums.

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It depends on who your ISP is. If you have an SLA on a business/enterprise class connection you are certainly guaranteed the speed quoted. –  MDMarra Dec 15 '09 at 15:56
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If you've got an iPhone, 'Convert' happily converts megabits to kilobytes, or even terabytes to gigabits -- if you're going to be making these estimations a lot, it can be a handy tool -- though Google certainly works, or your trusty calculator.

That said, on long-distance links the problem is frequently latency rather than throughput. This is especially true on single-stream activities, where you need to round-trip in order to send the next set of data. TCP connections in general can have these issues, which can be exacerbated by the protocol running on top of them. (CIFS is notorious for limiting throughput based on latency.)

A bunch of folks (including Riverbed) sell WAN acceleration devices that encapsulate TCP and send it by another protocol that has better characteristics on high-latency links. Depending on the workflow here you may want to look at those solutions.

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