Broadband Speed

4 minute read

The words Mega, Giga, Tera could well be the start of the names of various dinosaurs. Thankfully, in our world we’re surrounded by cables and radio waves instead. But these terms bear great significance. They are a unit for measurement which can quick become confusing.

Mbps, GB, MB – What do they mean?

We use both Megabit and Megabyte, Megabit being written as Mb and Megabyte being MB. This is the same for Kilo, Giga, Tera, Peta and so on (Gb, GB, Tb, TB etc). We use these units to represent a volume of data. If you want to represent a volume of data over a period of time (aka speed) then “per second” is used. You can append “per second” or “ps” to any unit to yield MBps, GBps, Pbps for example.

It can get a bit confusing, bits and bytes are two totally different scales but they are related. 1 byte is made of 8 bits. Broadband speeds are advertised in megabits, currently most ISP’s offer up to 80 Mbps download and 20 Mpbs upload on their highest packages. If you translate this into bytes you can get up to 10 MBps download and 2.5 MBps upload.

It’s worth noting that even if your broadband line syncs at 80/20 you won’t be able to “use” it all. There are various overheads caused by the protocols that transmit data. The difference it makes will be small but does vary.

What do I need?

Well, at home I have a 64 Mbps (ish) download and 13 Mbps (ish) upload - it was 20 upload but Sky have broken something and aren’t in a hurry to fix it. Anyway, here’s a graph from my router showing the last 24 hours of usage:

As you can see, what we actually use is much, much lower than what we could use. (It’s worth noting that this wasn’t a particularly intensive 24 hours). Let’s say you visit a website that is 2 MBs in total and for the sake of argument there’s are no overheads, waiting for the server or any other factors at play. That’s 16 Mbs and on a broadband line capable of 4 Mbps and would take 4 seconds to download. Now, let’s download the same thing on a broadband line that is capable of 60 Mbps - it only takes around a third of a second this time.

Here’s a more extreme example, the following is the total broadband usage of my family from the past 14 days:

The “Streaming Media” part doesn’t work for this argument as you’ll see in a second but the “Web/ Web 2.0” and “Network Protocol” parts are nearly entirely websites. If we were to download this 160~ GB in one go it’d take around 23 hours using a 16 Mbps download in our theoretical perfect scenario. The same could be achieved in around 6 hours on our 60 Mbps line. That’s a massive difference and although it’s spread out over 14 days we’d still be wasting hours. This is without taking into account all the real-life overheads and things.

Now, there’s also streaming (YouTube, BBC iPlayer, internet connected TV etc.) these all require continuous downloading. For instance, Netflix recommend a minimum of 5 Mbps for the streaming of HD content. To be sure there’s no buffering you ideally want a slightly faster speed than that. Then you should multiply it by the maximum number of streams you would ever have at the same time.

What defines my broadband speed?

Broadband speed is effectively defined by the quality and distance of your phone line. When you turn on your modem it and the exchange send each other signals in order to determine what speed the line is capable of - this is known as the “Sync Speed”.

Beyond your phone line is a cabinet. This cabinet is highly likely to be connected to the exchange via fibre optic cable (aka FTTC) and this has a much higher data rate. This means that the primary limitation is the sync speed of your phone line.

Choosing a broadband package

Personally, I’d always go for faster broadband were it to be available to me. However, for most people a 40 download 10 upload package would more than suffice if your line can handle it. Internet service providers (ISPs) will usually give you a pretty good estimate of the speed your line can achieve and you can choose from there.