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Broadband speeds: what to look for

Broadband can seem like a meaningless term because it means anything above 512Kbps – everything from a 3G smartphone getting 1Mbps to 120Mbps on fibre optic broadband.

These days you’ll also see ‘superfast’ broadband used for speeds of 20Mbps…and the world hasn’t settled on a term for the 100Mbps-plus speeds that fibre-optic broadband is delivering to more and more homes.

Broadband speeds

‘Up to’ speeds

Broadband providers usually quote an “up to” speed that’s the maximum you can expect if you live close to the local exchange and you have a good quality line and you’re not sharing it with a lot of other users. Indeed, providers often get their knuckles rapped by advertising regulators for being less-than-scrupulous in their top speed claims.

Ofcom is the UK’s communications industry regulator, and performs research on broadband speeds twice a hear. It’s most recent report, in November 2011 reported that “up to” speeds on ADSL are rarely anywhere near what’s claimed. On average, “up to 8Mbps” is about 4Mbps, while “up to 20/24Mbps” could be anything from 6-10Mbps.

Most UK broadband is ADSL, which uses the same copper wires as your BT phone line to deliver data from the local exchange to your home. The local exchange is connected via one or more regional hubs to a UK internet backbone, either owned by BT or another provider, like Sky.

BT Openreach sells broadband backbone capacity to most providers (except for Virgin and Sky) and leases all of the copper wires from the exchange to your home (except for Virgin) – known as the ‘last mile’. If you’re not sharing this last mile with many other people then you’ll get a faster, more reliable connection – this ‘contention ratio’ should be as low as possible, but that usually costs more.

Broadband speed test


Your distance from the local exchange can have a major effect on your broadband performance, and the oldest ADSL kit could only deliver a top speed of 8Mbps to about 2km. Newer ADSL2 can hit 12Mbps up to about 1.5km, and ADSL2+ goes to 23Mbps, but only for about 700m. By about 4km it doesn’t matter which standard you’re on – 4Mbps is the top speed you can expect. Added to that, some parts of the country have very old, very poor quality copper phone lines that privatised BT hasn’t replaced.

Fortunately you can get a simple answer to the question of distance vs speed with our Broadband Line Checker, and the contention ratio or type of DSL is what you pay for on top of that from your chosen provider.

Fibre broadband

Fibre optic broadband – as offered by Virgin Media and BT Infinity – has none of the distance restrictions of copper ADSL and can carry vastly more data, so contention ratios aren’t an issue.

However, it’s only available in certain parts of the country, and high speed fibre is still expensive for home connections, but speed claims for cable and fibre and very accurate. For more about fibre, see our guide What is fibre optic broadband?

So what will different broadband speeds let you do? Here are some typical examples at different speeds.

Speed (Mbit/s) MP3 album, 50MB (based on 10x5MB tracks)

200 photos, 200MB (based on 1MB JPEGS)

One hour standard definition TV show (350MB) Standard definition film (1.5GB) High definition film (3GB)
2Mb 5min 20min 34min 2h30m 5hours
10Mb 1min 4min 7min 30min 1hour
50Mb 11sec 47sec 1m20s 6min 12min
100Mb 6sec 24sec 42sec 3min 6min

(Please note: these speeds are estimates only and may be affected by other factors in reality)