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Old 11-05-2006, 00:02   #16
jem
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Join Date: Mar 2005
Location: SE London (Bexley)
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Re: 10 meg what download speed should i get

Quote:
10Mb = 10240kbps = 1280KBps. (roughly 1Megabyte per second)
Upload? 512? 512 = 512 = 64KBps (Roughly 64Kilobytes per second)
If its a 384 upload then it is...
384kbps = 48KBps (roughly 48Kilobytes per second)

Bits to bytes basically, 8 bits to one byte, and NTL measure there speeds in BITS. That means 1Mbit = 1024Bits = 128KBytes
This is not strictly true.
File sizes are measure in bytes and Kilo or Megabytes where (for various reasons its all based on powers of 2) one Kilobyte is 1024 bytes (2 ^ 10) and one Megabyte is 1024 x 1024 or 1048576 bytes (2 ^20). Note the uppercase K for Kilobyte - its significant.

Now for data transmission its a different story. Speeds are measured in bits per second and the standard SI system for units is used. i.e. one kilobit per second is 10 ^3 or 1000 bits per second. Note that here the lowercase k signifying the proper use of the kilo prefix is being used. Similarly a one Megabit per second download speed is equivalent to 10 ^ 6 or 1,000,000 bits per second.

So suppose I want to download a 5 Meg file using my 2 Meg line. The size of the file is actually;
5 X 1024 x 1024 or 5242880 bytes in size or multiplying by eight (eight bits in a byte) we get 41943040 bits in size.

My 2 Meg line should (ideally) download at 2,000,000 bits per second so I should be able to download the file in

41943040 / 2000000 seconds or 20.97 seconds.

In actual fact it will take longer than this as I haven't allowed for the TCP overheads.

But in answer to the original question on a 10 Meg line your should be able to download at 10 million bits per second and upload at 512 thousand bits per second - not that you'll actually be able to achieve this mind!
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