How Accurate Are Connection Speed Tests?

A digital speedometer

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The results of a speed test are rarely the same all the time. This is because there are a number of factors that affect them, some of which you can control while others not. The factors that affect the accuracy of a speed test are:

A Speed Test Is a Simulation, Not the Reality

What is the reality like? Whether it is browsing, whereby small HTML files are downloaded each time you click on a link or phoning, whereby voice packets are sent to and from your machine, the traffic activity is quite different from that of a speed test, which involves downloading a sample file. In consequence, the result obtained is not exactly what you experience when you use your connection.

The Test Server Location

If you choose a server that is quite far away geographically, your test might not be that successful. Choose one in your area (continent, ocean). Some tests suggest a suitable list of servers from which you can choose one.

Concurrent Internet Activity on Your Connection

If you have another application consuming bandwidth (like a file downloading), it will affect the test results. This is why there are some good practices for testing your connection, one of which is to make sure there are no other processes running on your machine that is actually consuming bandwidth. One easy way to do that is to have a network meter on your machine, indicating the presence and flow of bandwidth, 

Concurrent ISP Subscribers

At peak times, there is very often a drop in quality of connection with most ISPs. This is because many people are connected to the Internet through the ISP at that time. This will affect speed test results as well. Maybe one of the worst times to do a test is Saturday evening where most people are connected. 

The Use of Proxy Servers

If you are using, say, your corporate network at your place of work, there is a big chance that you are behind a proxy server, which is used to monitor and control internal networks. This, with NAT (network address translation), can affect the speed test results, because there are some special checks and additional activity at the proxy server.

Simultaneous Tests Being Run on the Same Server

Obviously, the more there are speed tests being done on one server, the more jammed the connection to it is. As a result, the test results will be affected.