What Do Those ‘AC’ and ‘AX’ Numbers on Your Wi-Fi Router Mean?

When it comes to product specs and model numbers, higher numbers are usually better. So is an AC2000 wireless router worth choosing over an AC1900 one? AX6600 has to be more capable than AX6000, right?

If you’re not sure, we get it. Router makers have adopted a complicated, confusing naming scheme that often differs among manufacturers and sometimes leaves you, the shopper, in the dark. Yes, those numbers are about speed, but they reflect speeds that you won’t be seeing on your phone or PC, because they’re the sum total of all possible speeds on all channels and all frequency bands that the router supports.

Dual-Band vs. Tri-Band

Wi-Fi 5 (AC) and Wi-Fi 6 (AX) routers are generally either dual-band or tri-band. Dual-band means they work on the 2.4GHz and 5GHz bands; tri-band means they have 2.4GHz and can simultaneously do channels in the lower and upper part of the 5GHz range.

With a tri-band router, you may be able to use the faster upper-range channel, or that channel may be dedicated to backhaul between units of a mesh system. (That depends on the router.)

In any case, that number on the router is the sum of all the possible bands the router can use, not the speed of any individual band or device. So if the combined speed of all of a given Wi-Fi 5 router’s bands is 1,900Mbps, you might see it advertised as AC1900.

Wi-Fi 5: Pick a Band, Not Both Bands

The most important thing to know about Wi-Fi 5 router speeds is that they’re a combination of the 2.4GHz and 5GHz speeds that the router supports, and a Wi-Fi 5 device connecting to it can pick only one. Most likely, you’ll be on 5GHz. So your laptop maxes out at 1,300Mbps on an AC1750 router. (See our chart below.)

Phones and smaller devices generally handle only one or two spatial streams. The Samsung Galaxy S21 and the Apple iPhone 13 both have 2×2 MIMO in their Wi-Fi. That means speeds no better than 867Mbps to each device when using an AC1750 router. (In my real-world experience, that’s usually really around 650Mbps.) A router supporting more streams means it can handle more devices at once that are running at the best possible speeds.

The above chart is mostly a chart of dual-band 802.11ac modes. The three at the bottom are tri-band modes, with two 5GHz channels running at once.

Wi-Fi 6: Bigger Channels, Higher Speeds

Wi-Fi 6 allows for faster speeds based on several new technologies. Better encoding and wider channels allow for more data to be carried on a single stream.

Otherwise, the same rules apply as with Wi-Fi 5. Your device has to pick 2.4GHz or 5GHz, and it may not be able to handle as many spatial streams as your router. Netgear gave us a list of their Wi-Fi 6 modes, and we added data from Asus and other router makers.

Tri-Band Wi-Fi 6: Faster Speeds (in the Background?)

Tri-band Wi-Fi 6 systems support both low and high 5GHz channels simultaneously. They may use the high 5GHz channels as dedicated backhaul for a mesh system, using them exclusively to pass data between the router units, so consumers may not be able to access that channel for their devices.

As you can see on this chart (primarily provided by Netgear, and enhanced by PCMag), tri-band mesh systems will have higher AX numbers even when the speed delivered to any individual device (on 2.4GHz or 5GHz) is the same as a standalone dual-band router with a lower number.

The “5GHz” columns in the chart refer to the lower 5GHz channel used by the router, and the “5GHz-2” columns refer to the higher 5GHz channel.

What About Wi-Fi 6E?

Wi-Fi 6E uses a new 6GHz channel to deliver even faster speeds to devices. But there are very few Wi-Fi 6E routers out yet, and they’re very expensive. (See, for example, our review of this Netgear Nighthawk Tri-Band 6E model.) At the moment, though, they seem to be following the same naming convention as other Wi-Fi devices; that is, the number is the sum total of all speeds.

Using a genuine Wi-Fi 6E client device, though, you’re likely to get higher speeds than on Wi-Fi 6, if your source connection is fast enough to handle it.

Router Numbers Versus the Real World

The most important takeaway here is that no single client device can ever get the maximum speed shown on a router box. These speeds are theoretical maximums, not real-world measurements. Here are some of the factors that conspire to limit speeds:

• Your device will be choosing among 2.4GHz or 5GHz frequencies, not combining both.

• The advertised speeds assume really strong signals! Speeds decline further with lower signal strength.

• Interference. There are only a limited number of Wi-Fi channels, and your network may be fighting with other nearby networks over them.

• Handheld devices like phones can use only one or two data streams. Laptops and desktop PCs handle one to three.

• Most laptops, tablets, and phones still don’t support the widest channels that routers do, 160MHz.

And finally…

• You can’t get a faster speed than your source connection can deliver. If you’re trying to download something over a 100Mbps Ethernet cable connection, you’re never going to get more than 100Mbps, no matter how good your router is. The pipe is the pipe.