How to check if your ISP is lying about your broadband speed

Your ISP and cell service provider spend plenty of marketing dollars touting their high broadband speeds -- but are they telling you the truth? Here's how to find out.

The first place to turn is the United States government, and the excellent, if little-known, Broadband Map. The site gives you ways to find out via maps more than you ever wanted to know about broadband use in the U.S., from type of broadband connection to how connected your community is, and more.

But if you want to see whether the broadband providers in your area actually deliver the speeds they promise, head to a map that compares the broadband speeds promised by ISPs versus the actual speeds delivered. Then click "Speed vs Advertised" at the top.

It's not a pretty picture. Areas that are slower than advertised are in pink and purple; areas faster than advertised are in green. As you can see, you won't find a whole lot of green. Most of the United States gets slower broadband speeds than promised. You can zoom in on your area to see what it's like near where you are.

broadband speed National Broadband Map

That gives you a general picture of things, but doesn't show your actual speeds. To do that, use one of the many free speed tests on the Web. My favorite, which I've been using for years, is It shows that at my house in Cambridge, my average speed is 94.57 Mbps, not much below the "up to" 105 Mbps that Comcast, my provider, advertisers.

There are a few things you need to do before taking the test. If you're testing a computer rather than a smartphone, plug it directly via an Ethernet cable into your cable modem or router --- don't test on a Wi-Fi-connected device. If you test on a Wi-Fi device, you'll really be testing the speed of your Wi-Fi network, not the broadband speed delivered by your ISP.

Also, make sure that no other devices are using bandwidth, especially any music or video streaming services, or downloading services or apps. In fact, you'd be better off if no other devices were actively using the Internet.

Also, run the test multiple times at different parts of the day. That will give you the most accurate numbers.

If you're testing your cellphone provider speeds, things get dicier. Rather than going to the Web on your phone, you'll be better off downloading the app for iOS and for Android. Make sure that no apps are running and that there's no data being downloaded in the background. And run multiple tests not just in different parts of the day, but at different locations, because there can be a dramatic difference between wireless broadband speeds depending on where you are.

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