ISP connections seem to be rated in download/upload speeds, with download
speeds being substantially higher. I’m often urged by my ISP to upgrade my
service to a more expensive option that provides higher download speeds. What
no one can explain is, how much faster can my download speed be if the servers
I visit are limited to the slower upload speed?
There’s a bit of a misconception built into the question that I want to try
to clear up.
Upload and download speeds aren’t related. Well, technically I suppose they
are, kinda, but for all practical purposes you should think of them as
So the fact that a much faster download speed is available actually has
nothing to do with the fact that your upload speed is much slower in
I know, it’s confusing.
The best analogy I can come up with is your car. You can travel forward much faster than you can travel in reverse. I’m not just talking about your skills as a driver, though I suppose that counts, I mean that your car is simply incapable of going as fast backwards as it is forwards. Your transmission, among other things, is simply geared that way.
And you probably don’t care.
Because you spend much more time driving forward. It’s how you get places. It’s much more important to you that you move forward quickly than it is you be able to backup at a breakneck speed.
Could a car be built that could go the same speed in both directions? Of course. But by focusing on one direction, by optimizing for forward motion, your car is more efficient at it.
The same is true of your internet connection.
You download much more than you upload.
A typical web browsing session might involve several small requests sent from your computer to remote sites requesting pages (anything sent from your computer to the internet is an “upload”, including requests to fetch pages), but the size of the pages and what they contain typically dwarfs the size of the original request by factors of 100 or even 1000 or more at times. A tiny 200 byte request for a YouTube video being uploaded could result in a download of many millions of bytes.
It won’t matter to you that the upload of that tiny request is somewhat slower as long as that huge download is as fast as it can possibly be.
The designers of the various technologies that we use to connect to the internet have realized this, and use it to “shift the balance” in your connection. Whereas in the past you might have seen 50/50 allocation in your bandwidth – half for uploading and half for downloading – the technologies being implemented in many cases effectively take away some of the uploading capacity in order to make the downloading speeds faster. Perhaps an 80/20 allocation of the available capacity instead: downloads are faster because you do them more, uploads are slower but you’re likely not to notice or care.
[I have to insert a note here to the pedants: yes, I know that I’m technically not exactly correct with this allocation metaphor, but it actually explains the concept very well. The fact is that technology, capacity, bandwidth and infrastructure are shifted in various ways from one direction to the other in order to provide a better user experience. The nitty gritty techie details are well beyond the scope of this article, or the needs of most of the people reading it.]
Not all technologies are “asymmetrical” – having different up and down speeds. Many dialup modems are (or were) symmetrical – having the same up and down speeds. DSL, more correctly ADSL for “Asymmetrical Digital Subscriber Line” was one of the first popular broadband connections to use this approach, and many others have followed in various ways. Other technologies remain symmetrical – connections between internet servers, for example, are very much like your own home LAN – the same speed in all directions. Some types of broadband, including connections such as the T-1 I use, are symmetrical by design as well. (I believe cable internet is asymmetrical, but I could be wrong. Most consumer and small business grade fiber, satellite and cellular broadband are all typically asymmetrical.)
Ultimately, unless you do a lot of uploading – running peer-to-peer software, uploading videos or the like – focus on the download speed. That’s what really impacts your internet experience the most, by far.