What’s in a Megabit?

January 21, 2010 - 7:36 pm

In the year 2000 less than 5% of the world’s population had Internet access. By 2003 that figure had doubled to 10%, then again by 2007. Now, approximately a quarter of the globe are considered Internet users, some 1.7 billion people. Over this time, the world population has grown by around 800 million people.

Sufficient to say the Internet has experienced colossal levels of growth in its user-base over the past 10 years. However, it’s not just the number of people using the Internet that’s grown, but also the amount of things it is used for. If the above figures didn’t make your head explode, perhaps these will…

In 2000, the cool thing to do was use a piece of file sharing software called Napster to download music from others (which of course we now all know is a naughty thing to do). Back then an MP3 music file would take around 10 minutes to download on a pretty good dial-up connection. To download a 30-minute TV episode from BBC iPlayer on that same connection would take over 12 hours!

The iPlayer and similar video streaming services have spurred massive growth in our data usage.

That’s 12 hours to download just over 300 Megabytes, something that today takes less than a couple of minutes on a broadband connection. Throwing a boulder into the already choppy waters of perspective, estimates for YouTube‘s data usage are in the order of 25 Petabytes, or over 27 billion Megabytes.

Phew, those are some scary numbers, right? Collectively we download an incredible amount of stuff, with no sign of our digital appetites easing up. So now that we have some perspective on things, let’s see how the figures advertised by our broadband providers map onto what we can get out of our connection. Time to slow things down a bit and get back to basics.

The first distinction to make is the difference between the Megabit and the Megabyte. Mega, loosely speaking, means a million of. Kilo means a thousand of something and Giga, a billion. OK, so we’ve got a million bits or a million bytes, what’s the difference? A bit is one single piece of binary information – a one or a zero, a yes or a no. A byte is eight of these bits, grouped together to mean something – a number, a letter, part of a picture.

When we store data and do things with it on a computer we tend to refer to things in groupings no smaller than a single byte. But when we’re sending data somewhere, be it down a telephone wire, network cable or a mobile phone, convention states we work in individual bits. We consumers are at the behest of industry standards here, so just be sure to remember that a byte is eight times bigger than a bit!

Better still, in communications, Kilo means 1,000 of something, but in computing it often means 1024 of something. This stems from the way computers represent numbers – don’t worry, we’re not even going to go there! We will say this though – if you stick to the “thousands” rule and a byte being eight bits, you’ll get ballpark figures, but they’ve not likely to be precisely correct. Still, what’s a billion give or take a few thousand?

What kind of Internet speeds can we get for our hard-earned, then? Most ISPs now offer services that are “up to” 8 mbps – that’s eight megabits per second. Depending on your phone line length, line quality, and how oversubscribed your broadband provider is in your area, you could end up getting anything less than or up to that, but never over what they’re advertising to you.

Some providers now offer higher speeds than this down a phone line – sometimes up to 20mbps or even 24mbps, achieved by using newer broadband technology. Again, though, unless you live very close to the telephone exchange, you might not get this.

Phone line length and quality often plays a big part in limiting broadband speed.

Cable broadband services work a little differently, and usually give connections at the speed they state – often 10 mbps, 20mbps or 50 mbps (with higher speeds on the way). But again, that’s only the speed between you and the other end of the cable – there’s plenty going on beyond that part of the connection that can slow things down!

One thing to remember then – don’t expect to get maximum speed, all of the time. In fact, don’t expect to get it very much at all! In 2009 Ofcom reported that the UK’s average broadband speed was 4.1 mbps, when the average maximum possible speed was 7.1 mbps. It’s a good job we Brits are a bunch of pessimists!

So what do our Internet speeds get us in terms of file downloads? Well, accounting for the conversions we need to do between bits and bytes, a typical 4 Megabyte MP3 (that’s 33.5 megabits, just in case you were wondering), will download in just over 4 seconds on an (actual) 8 mbps connection. That 30 minute iPlayer episode will take just over 5 minutes on the same connection.

Let’s break down some common entities into a table to paint a better picture of what these download speeds mean:

Hopefully that table gives you enough information to ascertain what amount you can download on a good day, and what you can download on a bad day, along with how long you can expect certain things to take on your connection.

“Streaming” services like iPlayer, YouTube and Spotify, let you play back music and video as they download – you don’t have to wait for the download to finish. But your connection needs to be fast enough to do this. If it isn’t, then the stream will stop and start – very annoying!

Another interesting point the table raises is that if you have a 40GB monthly usage allowance, it’s possible to use it all in half a day, assuming you have a perfect, 8 mbps connection in constant use. Of course, 40GB is a few dozen videos or hundreds of songs, so it’s difficult to achieve, but not impossible.

We hope we’ve given you some food for thought, and that we haven’t left you with a headache. But if we haven’t helped clear things up quite yet, feel free to ask your questions below!