When your internet starts feeling slow for no obvious reason, the best way to see if you've got a problem is to test your Wi-Fi speed. It's easy to do, and there are lots of Wi-Fi speed test services online that run in any web browser. They'll show you how fast your internet connection really is.

Here's how speed tests work, and how to make sure you have the best Wi-Fi speed.

How to Run a Wi-Fi Speed Test

Doing a Wi-Fi speed test is simple. Pick a service (see #1, below, for our recommendations), hit the big Go or Run Test button, then wait for it to finish. You won't be waiting long—the whole thing takes 20 to 30 seconds, tops.

speed test results

When you check your Wi-Fi speed, the test measures three elements:

  1. Ping rate or latency
  2. Download speed
  3. Upload speed

Here's what they mean.

Ping Rate or Latency

The ping rate measures the latency on a network. But what is latency? It's the time taken for a data packet to travel from the sender to the receiver, and back again.

High latency causes lag, which is something you definitely want to avoid in multiplayer gaming. A ping rate of more than 150 milliseconds could cause lag in gaming, while under 20ms is considered very low latency.

Download Speed

test download speed

Download speed is the most important figure. It signifies how fast data downloads to your computer, measured in megabits per second (Mbps).

The test works by downloading multiple chunks of data, adjusting their size and the number of connections as it goes. This maximizes the speed of your connection, ensuring it works at its fastest.

To judge the results, you need to know what speed of service you're signed up for, then compare them. For reference, Netflix requires 25Mbps for 4K streaming or 5Mbps for 1080p HD.

Upload Speed

A Wi-Fi test also measures the upload speed. This shows how quickly you can upload data, such as when you're backing up files to a cloud service. Compare your speed test result to your provider's quoted speed to see how well you're doing.

The upload test works the same as the download test, just in the other direction. Your browser uploads chunks of data, with adjustments made to ensure it uses the full extent of your connection.

Between them, the three tests will give a complete picture of how your wireless setup performs, and why your Wi-Fi speed drops.

You can use the results to find out if your internet speed is as fast as your provider promised, if it's fast enough for how you want to use it, and if you've got your router set up properly. But when you run a Wi-Fi speed check, make sure to avoid these common mistakes.

1. Don't Use the Wrong Speed Test Tool

xfinity speed test

When thinking about how to test your Wi-Fi speed, the first question to ask is which is the best speed test service to use? Some internet service providers, including Comcast, offer their own tool. If yours does, that's a good place to start.

If you want to check that your Wi-Fi is fast enough for TV streaming, try Netflix's Fast.com. It's no-frills, but connects to the Netflix servers so is accurate.

For the other options, just make sure you choose an HTML5 service over an older Flash one. Most Flash speed tests should have been phased out by now, but it represents another system overhead that could impact your speeds so is worth avoiding if you do find one.

speedtest app

Alternatively, forego the online speed test and use a dedicated speed test app instead. The desktop app from Speedtest.net is available for both Windows and Mac and makes the service a whole lot more accessible.

2. Don't Test the Wi-Fi Speed Only Once

speed test history

To get an accurate picture of your Wi-Fi speed you need to perform the speed test more than once.

Speeds can be quite volatile. You could do the test twice in the same conditions and get different results. By doing it at least three times, perhaps over a series of days, you can create an average of the results. This gives you a more accurate reflection of your actual internet speed.

3. Don't Test Wi-Fi at the Wrong Time of Day

One of the biggest factors affecting internet speeds is the number of your fellow users that are logged on at the same time. During "peak hours", like a Sunday evening when everyone's watching Netflix, you'll probably experience slower speeds than other times. Your speed test results will reflect this.

If you're trying to judge the performance drop-off during busy periods, then run the test at both peak and off-peak times and compare the results. If you just want to test your overall speed, stick to off-peak hours for testing.

4. Don't Do the Test in the Wrong Place

Doing the test in the wrong place will affect your Wi-Fi speed test results. But how do you choose the right place? It depends on what you're hoping to find out.

  • When you just want to measure your top Wi-Fi speed: Run the test with a close line of sight connection to your router. In other words, do it in the same room with no physical obstacles to block the signal.
  • If you're trying to find the best position for a router in your home: Run a speed test in every room, then compare the results. That will reveal any rooms that the signal is struggling to reach.
  • If you're trying to identify Wi-Fi dead spots or areas of weak coverage: Do the test in that spot and compare the result to one performed in perfect conditions. If this confirms a problem, you can then take steps to extend your Wi-Fi coverage.

5. Don't Leave Other Devices Downloading

A Wi-Fi speed test can only measure the speed attained by the machine you're testing on. For this reason, you should try to maximize the bandwidth available to that device.

Most of us have countless devices connected to our wireless networks, and the bandwidth from our internet connection is split between each of them. This causes the network to slow down, or at least appear slower on each device.

For best results, turn off or disconnect as many of your devices as you can, or make sure that none are downloading or uploading large files. You might want to learn how to pinpoint what's using up the bandwidth on your home network.

6. Don't Forget to Reboot Your Computer

reboot your computer before speed test

You can test your Wi-Fi speed on pretty much any device with a browser—from your laptop to an Amazon Fire Stick—but whatever you choose, you should always reboot it first.

Devices that haven't been restarted in a long time will have residual processes running in the background that can slow them down. This might affect your ping rate in particular.

Restart your machine and don't launch any other apps before you do the test. Keep an eye on what apps you've got set to launch on startup (a cloud app, for example, will go online to sync its data). You could even temporarily disable your antivirus software until it's done.

7. Don't Test While Using a VPN

Finally, make sure you aren't using a VPN, proxy, data-saving app, or anything else that sits between your computer and the internet. They can, and often will, slow down your connection, so using them while testing will not provide accurate results.

The exception is if you're looking for the best VPN and are trialing a few to see how fast they are. In that case, go right ahead.

What to Do With Your Wi-Fi Speed Test Results

A Wi-Fi speed test is useful for many reasons. The results will help in the following cases and more:

  • Making sure you're getting the speed you're paying for
  • Shopping around for a new provider
  • Setting up a new router and checking coverage throughout your home
  • Testing that your speeds are fast enough for your needs
  • Checking that your Apple TV, Fire Stick, or games console is getting good speeds
  • Finding peak and off-peak hours

When you're done, you might find that your internet is not as fast as it should be. And if your results aren't up to scratch, it's time to find out what's causing your slow Wi-Fi and how you can fix it.