Bytes, Bits, Mb/s and kbps someone explain please

[blizzard0c]

Ok,

I like to believe I have a well versed computer background but I think I am still getting confused on my connection speed test results.

I understand there are 1024 bits in a kilobite and 1024 kilobits in a megabit and so on.

I also understand that there are 8 bits in 1 byte.

B = Bytes and b = bits

So someone please explain to me why the possible equations to prove my results from 3 different sources do not equal out or make sense.

Keep in mind I have ran these tests back to back many times and randomly many times as well. These are consistant results for both sites with a very small margin. And the servers I am testing from are both within 50 miles of my house in the same direction.

The unit of measurment is typed exactally as it is in my results.

Here they are:

According to the following, is my speed:

My Router Claims that I have:

Download:25216 kbps

Up:2048 kbps

Bandwith.com (recommended by my ISP AT&T U-Verse)

Down:2456 kbps

Up:1345 kbps

Speedtest.net

Down:8.33 Mb/s

Up: 1.44 Mb/s

Edited September 15, 2009 by blizzard0c (see edit history)

[greywizard]

I understand there are 1024 bits in a kilobite and 1024 kilobits in a megabit and so on.

Wrong! There is no such thing as a kilobite, only kilobyte or kilobit.

I also understand that there are 8 bits in 1 byte.

Correct.

B = Bytes and b = bits

Correct.

So here we go:

1B (byte) = 8b (bits)

1Kb(kilobit) = 1000b (bits)

1KB(kilobyte) = 1024B(bytes) = 1024 x 8 = 8192b (bits).

So, for bits and their multiples you work always with powers of 10 (10^3 for Kb, 10^6 for Mb and so on) and for bytes and their multiples you work with binary powers (2^10 for KB, 2^20 for MB and so on). Usually all the network speeds both advertised and measured are expressed in bits' multiples (by your ISP, in technical documentations etc). On the other hand there are many software applications which express the download or upload speed in bytes (BitComet among them), and here's where you need to pay attention.

I have no idea what speed is your router measuring or how is it measuring that. Maybe it's the speed on the local loop between you and your provider.

The other two results are pretty close in terms of upload speed, it's the download speed that differs dramatically. Have you run the test on speedtest.net on several servers in different countries or just on one? You should run it on more servers from different countries and also go here for example and run the speed test on all available servers. This way you will get a better picture of what your real life speeds might be. I, too, have got some low speeds (much under my advertised one) on a few servers but on most of the ones I've tested (up to 30 at some point) they were fairly close to my advertised speed.

[kluelos]

Speedtest.net offers you the choice of units for measurement, so make sure you've set it up the way you intended and are measuring what you think you're measuring.

I believe your router is reporting your ethernet speed -- between your PC and your router. This isn't a terribly useful thing to know, not least because whichever connection is the slowest (that will be your modem) will bottleneck everything else.

When we get to the level of megabytes, agreement disappears. Some people hold to the power-of-two measurement, while others including many hardware manufacturers, firmly specify that a Megabyte is one million bytes. This position has gained a lot of support. Hard drive manufacturers in particular like this, because it lets them inflate drive size.

I wouldn't try to say which one is "right", but you do need to make certain of the definitions used by those you are communicating with. Fortunately, most of the time it doesn't really matter and we need consider only broad and general sizes & speeds. Precision frequently isn't very important here.