Helping people with computers... one answer at a time.

Bandwidth is a vague term that has at least two different definitions. I'll look at those as well as how uploading and downloading relate to bandwidth.

Not being too knowledgeable about bandwidths etc, I thought that all the massive movie streaming, TV catch-ups etc. that we're being urged to watch (and my wife does due to the hours she works) would use more bandwidth than just downloading file-sharing material or am I wrong? I have music playing on the internet all day, am I being greedy? What's an acceptable limit for daily use? Why don't ISPs give us programs and guides to let us monitor our usage? Why don't ISPs limit the amount of customers they take on if there's not enough to go around?? Getting back to the original question, I think I read somewhere that they can only track what we upload and not download, or am I wrong. It's all so confusing.

I agree it is confusing.

Fortunately bandwidth itself is pretty simple.

But the different ways that bandwidth can be used, and how it all adds up and how our ISPs limit and possibly monitor it is anything but.

I'll see if I can clarify a few things.

Bandwidth, Upload and Download

We need to clear a couple of things up.

First, bandwidth can mean either of two things:

  • The speed at which data can transfer to and from your computer.

  • The amount of data transferred to and from your computer.

"It doesn't matter how the data was transferred - data transferred is data transferred."

While the former will have an impact on how long things take, it's really the latter that we're talking about. ISPs tend to look at the amount of data that you transfer in a given time, and if there are restrictions in place called "bandwidth limits" or "caps", it's that they're referring to.

Second, data transferred is data transferred.

An "upload" is simply data transferred from your computer to a computer on the internet, and a "download" is simply data transferred from the internet to your computer.

It doesn't matter how the data was transferred - data transferred is data transferred.

Streaming versus Downloading

Time to clear something else up: "download" can mean two different things (no wonder it's confusing):

  • as described above all the data transferred from the internet to your computer

  • the process of transferring a file from some remote server to your computer

It's the first definition that matters when you're talking to your ISP about bandwidth caps and limits. All the data that gets transferred to and from your machine counts - it's all the same. It doesn't matter if you were streaming a video or downloading (second definition) that movie as a file, it all counts.

Which brings us to what I think is at least the first part of your question: streaming to view a movie once and downloading that same movie should count about the same against your bandwidth. In each case, the data that represents the movie is transferred from a server on the internet to your computer: in one case to be played immediately by a movie player, and in the other to be stored as a file on you computer's hard drive.

Now, there are naturally caveats since life couldn't be that simple.

You'll note I emphasized streaming the movie "once". If you watch it twice it will be streamed twice which means that the data that is the movie will be transferred to your computer twice, thus counting against your bandwidth limits twice. If you download that same movie to a file, you can watch it by playing that file as many times as you like without downloading it again.

One thing that could make a difference is that the quality of a video may be reduced when streaming, resulting in less data needing to be transferred to actually view it. Based on your connection speed, if it takes more than one second to download one second's worth of video then you'll experience hesitations and "buffering" as the player tries to catch up. One way streaming services deal with this is to reduce the visual quality so as to require less data which can transfer more quickly.

A downloaded file has no such restriction since you won't watch it until it's done. If it takes 5 seconds to download 1 second's worth of video you don't care, except that it takes 2.5 hours to download a 1/2 hour show. As a result, the quality of downloaded videos can be better. It's not always; it depends on where you're getting your video, but it's possible.

Streaming Music

Don't feel guilty.

Streaming music involves the transfer of data from the internet to your computer where it's played by a music player, so of course it "counts" against the bandwidth limits imposed by your ISP. The good news here is that it's typically much less data than video uses.

And if you're not running into overall bandwidth caps, I see no reason not to do it. You're not significantly impacting anyone else (unless you have a very poor ISP), and let's face it: you paid for that bandwidth, so there's no reason to be afraid to use it.

Why Don't ISPs...

Indeed, why don't they?

I can make a few guesses.

Many ISPs that impose bandwidth limits do provide you ways to monitor your usage. The best example are cellular providers who frequently provide account usage information in some sort of "My Account" web page. I know that both of the cellular providers I've dealt with recently do so as.

Similarly I'd expect a "traditional" ISP to do the same. If they're going to slap you for your bandwidth usage they should provide you with a way to check it. Programs on your computer are too unreliable, but web access to the information seems like a requirement.

Besides as another way to make money why are there caps at all? In part to control and predict the size of the infrastructure the ISP needs to service its customers. However ... it's no secret that if absolutely everyone connected to your ISP started using the internet heavily at exactly the same time, none of them would work. The phone company's the same way - if you've ever picked up your land-line phone in the middle of a local emergency you may find there's no dial tone - the phone system was never designed to have everyone talking at once.

And so it is with the internet. It's designed around a model that says "on average people use this much", and then the ISPs and other internet providers design their systems to handle 2 times that, or 4 time, or 10 times - whatever makes sense for their business model. Bandwidth caps are one way to reign in your usage to fit into whatever capacity they have.

What can the ISP See?

You read wrong. Your ISP can see everything; uploads, downloads - it doesn't matter. The bits all flow through the equipment operated by the ISP, and as a side effect it's very possible - easy even - for them to examine the data in various ways.

For the most part ISPs don't really care about what you up and download.

But clearly they care about how much.

Article C4627 - November 26, 2010 « »

Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

Alan O
November 30, 2010 11:19 AM

It is true that as you expand the denominator (time) of bytes/bits per second, data speed and amount of data transferred becomes the same, but saying that these are two different ways of looking at bandwidth is very confusing. It is better to look at bandwidth as simply the amount of data that can be transferred within a standard time period. This will allow users to compare the bandwidth they may be allocated.

Alex Dow
November 30, 2010 11:50 AM

Think of the Internet as being the Interstate-Highway System in the USA (Motorway in UK, Autoroute in France, Autobahn in Germany etc); and that you have to pay a fee to use the system, the ISP of those road systems using Automatic Licence-Plate/Registration-Plate Readers to identify and know whom to charge the fee to, ie which Bank Account to Charge/Debit.

Your communications over the Internet are split in to small packets, each with amongst other things, your own IP Address, the IP Address of the Web Page Provider etc, so that the packets involved can be routed correctly in each direction.

A simple count of each packet identification plus the cumulative size of those packets, then gives a measure of your use of the system.

Rather like those highway systems, in degree it is self-regulating.

At quiet times, you can join that highway without paying much attention to other traffic already on it.

At busy times, you have to check carefully to merge in to the main highway traffic.

Thus the principle is CSMA - Collision Sensing (and avoidance), Multiple Access. You'll find this mentioned frequently in Ethernet discussions.

Another way would be by Token Block, similar to railroad/railway systems, where the loco engineer/driver has normally the only Token to allow entry in to the next Section/Block.

On reaching the end of that Block, the Token is passed to the Signaller in the Tower, who then hands it to the Engineer who is next to work the Section in the opposite direction.

There are complex variations of this such as to allow a number of trains to work consecutively in one direction. The engineer is shown the Token at the entry point; but given a Docket or Ticket to proceed, the last train in the convoy taking the Token thru/through.

Until the physical Token reaches the far end, no trains are allowed to work in the opposite direction.

Thus your ISP and others can monitor the amount of use etc that is attributable to you.

Curt Strong
November 30, 2010 1:11 PM

Now I understand. Frustration is incoming UTubes. You want to enjoy, but they stop and start and are getting worse over time. My IP, tells me that this is due to the increase complexity on the generation of these Utubes. But they are getting less and less enjoyable due to expanding stops and starts. So it seems we never catch up nor can pay for enough road volume as you describe. Like a freeway parking lot.

November 30, 2010 3:18 PM

"In website hosting, the term "bandwidth" is often incorrectly used to describe the amount of data transferred to or from the website or server within a prescribed period of time, for example bandwidth consumption accumulated over a month measured in gigabytes per month." -

I've always thought there was an underlying analogy of information flowing along a band, and the width of that band determining the maximum rate at which the information could be transferred.

Sure, a download (or +upload, but my current ISP does not worry about upload) limit has dimensions of information / T (e.g. GiB / month), but the analogy does not normally work, as we are not transferring data at anything like a constant rate over the month.

Alex Dow
November 30, 2010 11:34 PM

For those whose background is Radio, Radar and TV Transmission and Reception, the Internet use of the term "Bandwidth" is misleading if not actually wrong.
I suggest that to comprehend its use for Internet measurements, it is more accurate to think in terms of CAPACITY.
Just like the Freeway Sytems, everyone is competing for use of that CAPACITY.
Any connection involving VIDEO of any variety, requires a lot of that limited CAPACITY, hence the UTUBE problems.
In part, one way to ease that congestion is to have the choice of using Video and Audio; or Audio only, as can be seen in SKYPE.
But that wouuld not accomodate the increasing use of the Internet for TV "on demand". As this market increases, it will "demand" more and more of the limited CAPACITY, so interfering with "simpler" uses such as e-mail.
With TV on demand, you could be viewing a movie, with your neighbor/neighbour starting to do so, say one second later, so doubling the load on the Internet.
Multiply that by all the neighbours you have, each one second apart!

As well as Bandwidth being used out of kilter to its origins, Speed is misleadingly used. The speed of electrical/electronic transmissions over copper cable is generally limited by its nature, to around one-third of the speed of light etc in "free space". At present, we do not have any means of improving on that.
Optical Fibre connections have similar but higher speed limitations.
AS the full expansion of "Mbps" shows, it is the number of "bits" that can be handled in a second which is used to define different DSL connection rates. All those bits travel at the same speed in the cable. So the typical Download Bits at say 8 Mbps travel at the same physical speed of 1/3rd Light Speed, as the Upload Bits at say 400 Kbps.

One way is to think of a constant-speed Ticker tape, passing in front of you, with messages displayed on it.
If LARGE Font is used, it will be easily read; BUT take a long time for any one message to be completed.
If small font is used, the message will complete more quickly, say half the time - BUT will be more difficult to read.

December 2, 2010 11:55 AM

AT&T uses Yahoo. My frustrations are more and more simply reading many imbedded links are stuffed into text that it is a constant pop up of advertisements which often the "X" doesn't even work. In addition, just getting to my home page etc. is relegated to sit there while huge advertisements are being loaded to the top of the page by Yahoo/AT&T. By charging more and more including the raises, the various plans from Basic speeds to what they call "lightning fast" fast becomes "not enough". I will quit Yahoo/AT&T as soon as it is convenient for me.

December 3, 2010 6:39 AM

In my opinion, andwidth caps really have nothing to do with clogged internet freeways. The ISP can increase its capability at any time it wants to.

This is not much different than the "old days" of dial-up when your connection speed depended on your ISP's hardware vs. number of customers. Remember??

Luckily for DSL and cable customers there is a lot of competition so their bandwidth caps are reasonably generous.

I love the Hughes Net commercial: "In the time that it takes you to download a song on dial-up, you can download a whole album on Hughes Net." Except that you can't download an album on their service or much of anything else unless you do it during their "free time", which is after midnight and before daylight.

We have Wildblue. There are three of us in the household. We cannot watch streaming video, listen to internet radio, watch uTube, or download games, videos, movies or music. We can receive and send e-mail and surf the web. Our download is limited to 17 Gigs (5.6 Gigs each) in a rolling month.

We cannot send large amounts of photos to Photo Bucket nor use online data storage to back up our hard drives. Our upload is limited to 5 Gigs (1.6 Gigs each) in a rolling month.

For this we pay $80/month.

Now with Netflix's "watch instantly on your TV" growing rapidly, it will be interesting to see how DSL and cable companies react.

Comments on this entry are closed.

If you have a question, start by using the search box up at the top of the page - there's a very good chance that your question has already been answered on Ask Leo!.

If you don't find your answer, head out to to ask your question.