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Why do speed testing sites giving varying results?

Lakin
Dabbler
Posts: 11
Registered: ‎18-07-2012

Why do speed testing sites giving varying results?

Apologies if this has been asked before.
My speed has dropped over the past few weeks. It is better now but not what it used to be.
I have been using various web speedtesting sites to see what my line speed is and am getting confused by the varying results. I know time of day, flash or java based tests etc can affect results, but different speedtesters give me consistent yet varying results.
For example, using the bt speed test I get the following:
---
Download speed achieved during the test was - 6.27 Mbps
For your connection, the acceptable range of speeds is 0.6 Mbps-7.15 Mbps.
Additional Information:
Your DSL Connection Rate :8.13 Mbps(DOWN-STREAM), 0.45 Mbps(UP-STREAM)
IP Profile for your line is - 7.15 Mbps
---
Yet a couple of minutes later on - http://www.cnet.co.uk/broadband-speedtest/ - I got a speed of 2.2mbs. (Up until a few weeks ago this used to consistently showed speeds of about 5.4mbs)
A couple more minutes later the BBC Iplayer speedtest (which I like) shows my download speed as:
--
Download speed 6159 kbps
Streaming speed (1) 3371
Streaming speed (2) 2330
Streaming speed (3) 2163
Connection speed 2621 kbps
--
I know these speeds are not dreadful, but I don't understand why I get varying results and therefore don't know which result to trust.
7 REPLIES 7
orbrey
Plusnet Alumni (retired)
Plusnet Alumni (retired)
Posts: 10,540
Registered: ‎18-07-2007

Re: Why do speed testing sites giving varying results?

Any speed test result will vary from the next due to differing network conditions etc, there's so many variables there it's not really worth going into but include such things as number of people online, how many are accessing the speed test, how many connected to your exchange etc etc.
Can't advise much regarding the cnet speed test as I've never done one but I suspect that site is classed as a download site in our traffic management platform and if the speedtest files are coming from the same domain that would explain it.
Not sure what's happening with the BBC iplayer test there, but the download speed looks spot on for the BT speed test result. If I were to recommend trusting one over the other I'd say go for the BT speed tester as that's the only one they'll accept results from if we need to raise a fault for you.
Hope that helps.
Anotherone
Champion
Posts: 19,107
Thanks: 457
Fixes: 21
Registered: ‎31-08-2007

Re: Why do speed testing sites giving varying results?

Matt's explained a number of reasons for different results, you can add the number of people accessing the BBC to the pot for that result as well, BUT what time was that test run, as you said, it's not a good result. Keep checking that one periodically especially off-peak. If it is still giving poor results, something is amiss, possibly a Plusnet Network issue.
If that result was earlier today, before or around this issue that may have had a bearing.
Lakin
Dabbler
Posts: 11
Registered: ‎18-07-2012

Re: Why do speed testing sites giving varying results?

Thanks for your input and patience chaps. I know this is a 'how long is a piece of string' type of question.
I did the BBC test this afternoon, perhaps around 2:00.
The BBC result is the most important to us as it is a 'real world' test (I think). Up until recently we have been lucky in that we could watch iPlayer programs with no issues. But increasingly we had constant buffering and pausing, which is why I started looking into my broadband speed with varying results. Hence my question.
Tests that show what the ideal speed I could get is are of little use e.g. the BT Broadband Availability Checker test shows:
"Your exchange is ADSL enabled, and our initial test on your line indicates that your line should be able to have an ADSL broadband service that provides a fixed line speed up to 2Mbps.
Our test also indicates that your line currently supports an estimated ADSL Max broadband line speed of 5.5Mbps; typically the line speed would range between 4.5Mbps and 8Mbps."

I want a test which can accurately tell me what I am getting.
I could run as fast as Usian Bolt given the right conditions, but probably never will.
Anotherone
Champion
Posts: 19,107
Thanks: 457
Fixes: 21
Registered: ‎31-08-2007

Re: Why do speed testing sites giving varying results?

With an IP Profile of 7.15MBps you really ought to be doing a little better than 6.27 on the BT Speedtester. Check what your Current Line speed is at the Member Centre (login required). It should match the BT IP profile.
As has already been said that iPlayers result is not good.
Lakin
Dabbler
Posts: 11
Registered: ‎18-07-2012

Re: Why do speed testing sites giving varying results?

Hi Anotherone,
The link you gave showed this:
Current line speed:
    7.15 Mb

I opened another question to the support team last night because iPlayer stopped playing properly. This was at about 9:30.
I rebooted my router and ran an iPlayer speed test that gave me:
--
Line speed: 1549kbps
Download speed: 3337
Streaming speed (1) 2049
Streaming speed (2) 1119
Streaming speed (3) 1479

--
I then ran a couple of speedtests via my account page (I know it is still saying the results my be inaccurate) that gave me:

Today 21:57 2577 kbps (322kB/s) 367 kbps (45.9kB/s)
Today 21:45 2149 kbps (269kB/s) 351 kbps (43.9kB/s)
Today 21:45 2524 kbps (316kB/s) 367 kbps (45.9kB/s)

orbrey
Plusnet Alumni (retired)
Plusnet Alumni (retired)
Posts: 10,540
Registered: ‎18-07-2007

Re: Why do speed testing sites giving varying results?

Hmm, profile's at 7150 so it doesn't look to be affecting your profile but there are one or two disconnections showing:
<img src="http://ccgi.psmith12.plus.com/visradius/generated/image13426927158502.png" />
I guess this is you rebooting the router rather than any sort of drops? If not that may be worth looking at.
Lakin
Dabbler
Posts: 11
Registered: ‎18-07-2012

Re: Why do speed testing sites giving varying results?

Hi Matt,
Yes they were reboots.