a blog from CenturyLink

Understanding internet speed and WiFi

by | Apr 14, 2021


Chances are good you’ve spent at least a moment or two thinking about your internet speed — especially if you’ve experienced a slow or spotty connection. You may have run a speed test, or you may have no idea what your internet speed is.

Either way, if you’re like a lot of people, you simply want to know: “Is my connection fast enough?”

To really answer that question, you must understand a bit more about internet speed, WiFi speed, and network connections. So let’s jump in.

What’s the difference between speed and bandwidth?

You may hear “bandwidth” and “speed” used interchangeably, but they do refer to slightly different aspects of internet service.

  • Bandwidth is the maximum volume of data that can be transmitted over an internet connection, measured in Megabits per second (Mbps).
  • Speed is the rate at which information or content reaches your device (tablet, laptop, smartphone, etc.) from the internet. This is also measured in Mbps.

There’s a plumbing metaphor that can help us understand these two concepts. Think of bandwidth as the width of a water pipe, which determines the volume of water that can flow through the pipe at any given moment. The speed, then, is how fast that water comes out of the tap when you turn it on.

Information flows over your internet connection like water through pipes.

So, if your internet plan has an advertised bandwidth of up to 20 Mbps, this is the highest volume of information that can be sent over the network to your router. From the router to your devices, then, the speed you see will typically be a bit lower. That’s because once the connection is divvied up by the devices in your home and sent over WiFi, some of that network speed is lost.

What does your speed test tell you?

Many internet speed tests out there, including the one we provide here, on the CenturyLink site, measure internet speed on a particular device. In this case, you have to take a few things into consideration before you can determine if the test results are “good” or “bad” for your situation.

Note that another type of speed test, such as those offered by certain modem manufacturers, measures the speed from the network directly to the modem. In that case, the information below would not apply, as the results would not change based on these factors.

Factors that impact your test results

The speed test measures the flow of data at one moment in time. The results tend to fluctuate depending on a number of factors:

  • Whether you’re testing over WiFi or over an Ethernet (wired) connection to the router
  • How many devices are running on your home network (and how intensive your online activities are at that moment)
  • The time of day
  • Which device you run the test on, and how old it is or what its speed capacity is
  • Which test server is used

How does an internet speed test work?

When you run an internet speed test, the testing site transfers a file from a nearby test server over the internet to your computer and measures how long it takes. That gives you your download speed. Then that same file is transferred back to the server again to measure the upload speed. The test will automatically select the closest server, which will typically be in a nearby city.

When the test is done, you’ll see your results as two numbers reflecting the download and upload speeds. One megabit is roughly equal to 1,000 kilobits, which means 1 Mbps is 1,000 times faster than 1 Kbps. Similarly, 1 Gbps is 1,000 times faster than 1 Mbps.

On your internet plan, you may see something like 40/20 Mbps (or “40 by 20 Megs” in the industry lingo). This is shorthand for 40 Mbps of download bandwidth and 20 Mbps of upload bandwidth. These “asymmetrical” speeds put the “A” in ADSL connections, which have higher downstream bandwidth than upstream bandwidth.

One of the awesome advancements in internet technologies is the increased capacity for upstream bandwidth. This is leading to more internet plans that have what they call “symmetrical speeds” or equal download and upload speeds. With high-speed fiber internet, for instance, you can get speeds up to 940/940 Mbps. That means information can pass into and out of your devices at the same super-fast rate.

While the speed test runs, it also measures several other aspects of internet speed. Each speed test may have slightly different features, but many of them measure ping and jitter.

What is ping (latency)?

Ping is the measure of latency from your device to the server and then back to your device. Essentially, it is one of the elements of connection speed that measures any lag you might experience while online. Lags are typically most noticeable when streaming music or HD video, gaming, videoconferencing, or doing other high-bandwidth activities. Ping is measured in milliseconds (ms), and the lower the number, the less lag you’ll get. Generally, a ping value under 50 ms is good and over 100 ms is poor.

What is jitter?

Jitter tends to be less important to many internet users, but gamers are often concerned about both ping and jitter. Jitter is essentially a measure of the variation in ping over time. This is given in a percentage. A lower percentage is better, because it means the connection is more stable.

Some sources say you want to have a ping of less than 200 ms and a jitter of less than 15%, but this can depend a lot on what types of online activities you like to do. Avid online gamers, for instance, will want to shoot for even lower ping and jitter numbers.

Latency (ping) can cause lags and buffering while streaming video

What impacts your internet speed?

Not surprisingly, the factors that affect the results of your speed test are the same factors that impact the real-life speeds you experience while working, schooling, streaming or surfing.

Below are some of the key factors that contribute to your internet connection speed:

1. The network speed from your provider. This is the first one that many people think of, and it definitely plays a role. Most of the time, though, the connection speed of the CenturyLink network (or any internet provider) stays pretty consistent within a given range. In other words, the network speed that comes into your router from outside doesn’t fluctuate as much as the speed you experience on your side of the router (on your devices).

Illustration showing network speed to home

2. The speed of your devices. Each device, from desktops to tablets, and from smartphones to smart televisions, has its own speed limit, which in some cases may not be as fast as your internet service. The newer the device, the more likely it is to have a faster processor, as well as additional wireless antennas that allow it to send and receive data over WiFi much faster. Older devices can even slow down the speed you get on another device. How? All the information traffic from your entire home network has to wait in line to pass through your router, and older devices with slower connections can cause delays for any traffic lined up behind them. The same is true for your router, which is why it is recommended that you replace this essential equipment if it is more than 3-4 years old. The type of device also matters; smartphones today typically have one to two wireless antennas built in, while laptops are likely to have three to four. In other words, your laptop is likely to have a slightly faster WiFi connection than your smartphone.Illustration of older vs. newer devices impacting speed

3. Your WiFi use. Wireless connections have become such a standard that many people forget there’s any other way to get online. But there are benefits to accessing the internet over cables instead of over air waves. We all love WiFi because it gives us the ultimate mobility, but some connection speed is always lost in translation from the router to the wireless signal. This is why many blogs and tech experts out there (including us) suggest using a wired connection — a LAN or Ethernet cable plugged into the router from your device — when you can. This will give you a faster, more stable connection, especially for online gamers and others with particularly high bandwidth demands.

Alternately, WiFi extenders and signal boosters are popular for their ability to help overcome signal loss. And, when you’re using WiFi, you will get the strongest signal by being closest to your router with as few devices connected as possible. Using a 5 GHz WiFi frequency can help too. Why? WiFi is just one of many radio frequencies all around us these days. Devices that use the same 2.4 GHz frequency range as some wireless signals, such as microwaves, cordless phones and more, can hurt your internet speed. Many newer routers also support automatic band-switching, meaning they will detect and switch devices to a faster frequency without you having to go in and select a different network manually. Just keep in mind that with a 5 GHz WiFi frequency, the signal is faster but covers a smaller area. So it’s even more important to close the distance between your device and the router as much as possible, and to make sure there are no major physical obstructions blocking the signal’s path.

Illustration of multiple devices impacting internet speed

4. The number of devices using up your bandwidth. All the devices in your home share your internet connection. So the number of devices running at the same time impacts your internet speed significantly. Imagine your total bandwidth is a pie, and each device that is connected to the internet at one time takes a piece of that pie. The fewer the devices, the bigger each piece of pie, meaning the faster the speed. But the more devices you start adding to the network, the less speed each one of those devices will display.Illustration of bandwidth usage by various devices

5. The speed of the sending party. Especially during peak hours, certain websites or apps can get bogged down due to high demand on their servers. These high-traffic platforms can make it seem like you have a slower connection when you’re visiting them. Similarly, content occasionally has to pass through peer networks that have data caps or bandwidth limitations, which could cause you to see less than top download or upload speeds as you send and receive information. Going back to our plumbing idea, imagine a massive network of pipes connecting to your computer. There are different sizes of pipes linking multiple servers and routers that make up the world wide web. As the water (content) flows through all the different pipes, a narrow pipe anywhere along the line will limit its total speed as it passes through. Similarly, if any part of the network has lower bandwidth or is congested, this can impact your internet speed.

A number of other factors can impact your internet speed as well, including the distance from your router to your device, the age and type of modem/router, the type of technology used for your internet connection (copper, fiber-optic, etc.), and even the age of wiring inside your home or building.

See for yourself

It can be helpful to run multiple speed tests while changing some of the key factors mentioned above. This may give you a more complete view of your speed in different situations.

For instance, try some of these variations and compare your results:

  • Test on different devices (tablet, laptop, mobile phone).
  • Instead of testing over Wifi, test on a computer plugged into the router with an Ethernet/LAN cable.
  • Test first thing in the morning, again in the middle of the day, and again late at night.
  • First, test when the whole family is online. Then run it again when only one or two devices are connected to the internet.

If you’re not up for experimenting, simply understand that every one of these factors comes into play when you consider your connection speed at any moment.


A family uses their connected devices around the table

So… is my internet speed good or not?

We circle back to where we started — that ultimate question every internet user really wants to answer: is my internet connection fast enough? Now that you understand how the pieces fit together, you can answer that question for yourself.

As you do, here are a few final points to keep in mind:

  • The FCC presents a general guideline to household internet usage. The definitions of basic, medium and advanced service relate to the number of users/devices and the degree of internet use.

Basic service (Low speed) = 3-8 Mbps

Medium service (Average speed) = 12-25 Mbps

Advanced service (High speed) = Over 25 Mbps (this is the FCC’s definition of broadband internet)

  • A user often won’t notice the difference between, say, a 20 Mbps and 5 Mbps connection when doing most online activities. However, as you add people and more devices all running at once, you are more likely to notice buffering, lags, or congestion at lower speeds.

If you determine that your speed is not sufficient for your home’s needs, then there are a few actions you can take:

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<a href="https://discover.centurylink.com/author/jennifer-fossenbell" target="_self">Jennifer Fossenbell</a>

Jennifer Fossenbell


Jennifer Fossenbell enjoys the internet and enjoys writing about many things, including the internet. She lives in the Denver area with her children and spouse, who also enjoy the internet. She also enjoys traveling and eating around the world, making poetry and art, and standing in the forest. More at jenniferfossenbell.com.