How Do Internet Speed Tests Work? (And How Accurate Are They?)

How Do Internet Speed Tests Work? (And How Accurate Are They?)

A speed test is a quick way for you to figure out how fast your internet is. ISPs(Internet Service Providers) do promise an “up to” certain speed under optimal conditions. A speed test confirms how fast—or slow—your connection is.

What is a Speed Test?

An internet speed test is the best way for you to get an idea of how fast your connection is. The service you connect to often limits your download as well as upload speeds based on the plan you select, local congestion. Including any throttling rules, it has, among others.

The catch is the promises your Internet Service Provider makes always include the phrase, “up to.” This makes for an ISP wiggle room. For example, if they promised you “up to 30 Mbps,” and you consistently receive 28 Mbps, then the company can say it has kept the promise. However, if you are getting 10 Mbps, then you’re not getting what you are paying, it’s time you call your ISP.

A Speed test will measure your ping, your download as well as upload speeds. Measuring the latter two is essential as many ISPs make different promises for download and upload speeds. Usually, the download speed features prominently. However, if you dig a little further, the ISP typically specifies a slower upload speed for every level.

How does a Speed Test Work?

When you start a speed test, multiple things take place. First, the client will determine your location, it will determine the closest test server to you. Some versions, like Ookla’s Speedtest.net, provide you with an option to change the server. With the test server in place, the Speed Test sends a signal (a ping) to the server, which then responds. The test will measure the roundtrip in milliseconds.

After the ping is complete, the download test will begin. The client will open multiple connections to the server, then attempt to download a small piece of data. During this, two things will be measured: 

1. How long does it take to grab the fragment of data, 

2. How much of your network resources are used.

If the client detects you have room to spare, it will open more connections to the server, then it will download more data. The general idea is to tax your internet connection to see how much it can do at the same time.

After the client determines it has the correct connections to test your service, it will download additional chunks of data, and measures the amount downloaded in the time allotted. Then presents a download speed.

Next in line is the upload test. This is essentially the same process as the download test; however, this is in reverse. Instead of pulling data from the server to the PC, the client will upload data from the PC to the server.

If you want to know about this in more detail with technical information, check out Speedtest.net’s explanation.

Are these Speed Tests even Accurate?

Let’s consider the first step of the process. Choosing a test server. Often the closest server might be close, it may even be in the same city. The proximity is an optimal situation, thus meaning the data does not have to travel far. Businesses know that this proximity makes a difference. That is why some, for example, Netflix, use a content delivery network to bring the data closer to you.

However, the entire internet is not close to you. Much of it is on computers far away, maybe across the country or in a different country altogether. So, while these speed tests may show incredibly fast streams. You might notice that downloading a program is very slow, this happens if the server hosting the data is far. In that scenario, the results may reflect a faster performance than the real world.

The difference in server locations might be the reason you likely see different speed results when using different tests, like Ookla’s, Netflix’s, or Google’s. You probably shouldn’t rely on an ISP-generated speed test, because their tests would be optimized for ideal conditions. Use servers close to you that are often maintained on the same ISP network you are testing from. This means you will receive a faster result than what you might get when using a Netflix or Google speed test.

In step two of the process, the client attempts to open additional connections to maximize the network usage. If you are already burdening your network, then the speed test will not be able to take full advantage of the resources. If you perform a test while streaming Netflix. OR. While downloading a large update, your results will likely be lower than when you perform a test without any of these runnings.

How you’re connected and which devices you’re testing also affects the test results. An ethernet-connected PC will have a faster speed result than a Wi-Fi-connected tablet. This is because, generally, Wi-Fi is slower than ethernet. You might notice that results vary on different devices, even if the same connection is being used.

How can you Get the Most Accurate Results?

Getting accurate test results depends on what you want to measure. Do you want to see if your ISP is providing the speeds it promised? Then test in optimal conditions. Use an ethernet-connected device, choose the test server that is in proximity to you. Also, it is better to stop anything that might be taxing the internet connection.

You might even want to restart your router before you run a speed test. If your router has a built-in speed test, you can use that instead of a browser test. Doing so will remove some of the hoops that have to be jumped through.

However, if you want results closer to real-world performance, use a browser test. Bypassing the router test will let you pick a server that is far away. If you regularly have one or two video or audio streams running, start those before you start the internet speed test.

No matter which steps you take. OR. How you measure, you will not receive a super accurate result. However, you will get a good enough result to satisfy your curiosity. OR. To check the speeds promised by your ISP.

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