Windows iperf3: Difference between revisions

If you're needing to speed-test your internet service then you can use web-based speed testers such as https://speedtest.aa.net.uk, but they may not always give you accurate results. An alternative is using a tool called iperf3 to run a speed test against an iperf3 server that is hosted at your ISP.

iperf3 is a program that is easily installed on many Linux distributions, but is a little harder to use on Windows.

Here is how to download and run iper3 on Windows and how to test single and multi-thread upload and download speeds. - This uses the Andrews & Arnold speed test server, which is only available to customers.

The version of iperf3 we have here is 3.13 from Github built with cygwin. It's a newer version that is hosted on the iperf.fr website and so has a lot of bug fixes. - Thanks to ''Thomas Jepp'' for compiling this.

===1) Download...===

Download '''[[Media:Iperf-3.13-windows-x64.zip]]''' and save it to your computer, eg in your Downloads folder. (The usual caveats apply when downloading files from untrusted sources...)

===2) Extract... ===

===3) Open Command Prompt...===

Open up the Command Prompt - Click '''<SyntaxHighlight inline>Start</SyntaxHighlight>''' then type '''<SyntaxHighlight inline>cmd</SyntaxHighlight>''' and click on the 'Command Prompt' icon.

===4) Find the files...===

In the black box type: '''<SyntaxHighlight inline>cd Downloads\Iperf-3.13-windows-x64\iperf-3.13-windows-x64 </SyntaxHighlight>'''

You can check if you're in the right place by typing '''<SyntaxHighlight inline>dir</SyntaxHighlight>''' and you should see some files including '''<SyntaxHighlight inline>iperf3.exe</SyntaxHighlight>''' listed.

===5) Run iperf3 ===

Test it by running a simple speed test by typing: '''<SyntaxHighlight inline>iperf3.exe -c speedtest.aa.net.uk</SyntaxHighlight>''' (you may need to click 'allow access' if a Windows Defender window pops up.

By default, this will run a single-thread upload speedtest (sending traffic TO the speed test server). As you can see in the screenshot, the upload speed this line happens to get is just over 19Mb/s.

There are various other useful tests you can run, see the variations below.

===6) Send us the results===

You can copy all the text in the Command Prompt and email it over to us: Pressing '''<SyntaxHighlight inline>Ctrl-A</SyntaxHighlight>''' (The Control Key and the A key) will select all the text, and '''<SyntaxHighlight inline>Ctrl-C</SyntaxHighlight>''' will copy it to the clipboard. You can then open up your email and paste it in to the message.

=Variations=

There are variations you can do to test the speed as follows by using the '''-R''' (reverse) and '''-P''' Parallel options, we've also included a timestamp and a title to help with the logging:

* Run a '''single-thread Download''' test: <SyntaxHighlight inline>iperf3.exe --timestamps -T "1xDOWN" -R -P1 -c speedtest.aa.net.uk</SyntaxHighlight>

* Run a '''single-thread Upload''' test: <SyntaxHighlight inline>iperf3.exe --timestamps -T "1xUP" -P1 -c speedtest.aa.net.uk</SyntaxHighlight>

* Run a '''10-thread Download''' test: <SyntaxHighlight inline>iperf3.exe --timestamps -T "10xDOWN" -R -P10 -c speedtest.aa.net.uk</SyntaxHighlight>

* Run a '''10-thread Upload''' test: <SyntaxHighlight inline>iperf3.exe --timestamps -T "10xUP" -P10 -c speedtest.aa.net.uk</SyntaxHighlight>

* You may want to run the tests at different times of day so as to see if there is any peak-time congestion affecting you.