Wi-Fi Bandwidth 101: Best Tips on Dual-band vs Tri-band vs Quad-band

How the Wi-Fi bandwidth works has always been a mystery — we can’t put our finger on it. The hyped-up numbers thrown out by networking vendors’ PR campaigns only confuse things.

And then the number of bands you can find in a router has also slowly changed as Wi-Fi evolves. When buying a router, we now have the issue of Dual-band vs Tri-band vs Quad-band; each can be confusing in and of itself.

Starting with Wi-Fi 6, then Wi-Fi 6E, and especially the upcoming Wi-Fi 7, it’s evident that not all broadcasters — namely access points, routers, or mesh systems — with the same number of bands are created equal.

I’ll explain the differences between these band combos and run through some history in Wi-Fi bands. It’ll be a long read, but it’s worth it.

In case you’re in a hurry, though, here’s the gist: It generally doesn’t hurt to go with the most bands possible, but most of the time, investing in an additional band is not money well-spent unless you have a fully wireless mesh setup.

OK, let’s start with dual-band.

Dong’s note: I first published this post on October 28, 2019, and last updated it on February 10, 2023, to include relevant and up-to-date information.

Dual-band Wi-Fi (2.4GHz +5GHz): It’s all about compatibility

Dual-band goes back to the 802.11n Wi-Fi standard — or Wi-Fi 4 as it’s known nowadays. This standard first became commercially available in 2009.

Things were still simple then, and dual-band routers came into existence because we needed them. At the time, the 2.4GHz no longer cut it.

2.4GHz: The first band for Wi-Fi

Indeed, initially, Wi-Fi — then called “wireless networking” via the 802.11b (Wireless-b) and 802.11g (Wireless-g) standards — started with only the 2.4GHz frequency band — a radio component that broadcast signals outward — which was, and still is, too ubiquitous.

Besides Wi-Fi devices, cordless phones, Bluetooth gadgets, and home appliances (like microwaves) also use this frequency. It’s saturated.

Available to too many applications, 2.4GHz generally suffers heavily from interferences. Soon after its introduction, it quickly proved unreliable and too slow for networking, especially in urban areas. And that has remained until today.

That’s when the 5GHz came into play.

5GHz: The beginning of the Dual-band concept

5GHz was first available in 802.11a standard, or Wireless-a. For a short period, it was considered a single-band solution that could even slowly replace 2.4GHz.

While the 802.11a standard was first published at about the same time as 802.11b in 1999, the latter was more successfully commercialized. By 2000, 802.11b was quite popular, whereas there was no Wireless-a product until 2002.

So, for a brief moment, we had selectable Dual-band routers that do either 2.4GHz or 5GHz at a time.

But due to its shorter range, the then not-so-fast speed, and the fact that there were many 2.4GHz-only clients, 5GHz couldn’t survive on its own. Nobody wanted a 5GHz-only router.

As a result, starting with the 802.11n standard, we’ve always had the Dual-band concept: The co-existence of 5GHz and 2.4GHz.

A Dual-band Wi-Fi router delivers performance (5GHz) and backward compatibility (2.4GHz). Everyone was happy and remained so for about half a decade.

The original Tri-band concept: It’s all about the perceived extra bandwidth

Things started to change in 2014 as hardware vendors introduced the first Tri-band concept. It began with the 802.11ac standard, or Wi-Fi 5 as we know it today.

To understand the idea behind Tri-band, though, we first need to understand three things:

1. A Wi-Fi connection takes place on a single band and uses a fixed channel width at a time.
2. On a particular Wi-Fi band, only one channel can be active at a given time. You can combine channels into a single larger one but can’t use two or more separate ones simultaneously.
3. The bandwidth of a Wi-Fi band is shared — each connected client only gets a portion of a band’s total capacity.

Understanding Wi-Fi router’s bandwidth

Take the Asus RT-AX89X, for example. It’s a Multi-Gig Dual-band AX6000 router. Let’s break that down:

• Multi-Gig: It has two 10Gbps network ports (in addition to a load of Gigabit ports).
• Dual-band: The router has 5GHz and 2.4GHz bands that can work simultaneously.
• AX: is short for the 802.11ax standard (or Wi-Fi 6).
• 6000: The rounded combined bandwidth of the router’s 4800Mbps speed on the 5GHz band and 1148Mbps on the 2.4GHz band. The idea suggests that the router can deliver up to 6000Mbps at a given time.

Since a Wi-Fi client can only connect to a router using one band at a time, the best wireless connection you can get out of the RT-AX89X is 4800Mbps (5GHz) if we use a four-stream (4×4) client. With a 2×2 client, we get 2400Mbps at best.

But that’s only when there’s just one client. If you have two clients connecting and active simultaneously, each gets only half of that bandwidth. If you have ten simultaneously active clients, each now connects at around 480Mbps, or 48Mbps if you have 100 clients.

The real-world speeds are always much lower than that. And the Tri-band concept started with Wi-Fi 5, which has a lower ceiling speed per band than Wi-Fi 6.

Bandwidth: Wi-Fi vs wired

The real-world Wi-Fi speeds are always markedly lower than the standards’ theoretical numbers.

For example, a typical 2×2 Wi-Fi 6 (at 80MHz) connection might have a negotiated speed of 1200Mbps. But in my testing, the sustained rate registered around 800Mbps, at best. Most of the time, you can only expect half of that.

Due to the nature of radio transmission, Wi-Fi is susceptible to interference and has a lot of overhead. And data connections require a lot more bandwidth than radio signals.

And that’s why wired connections are generally superior in terms of throughputs. A Gigabit connection via a network cable has a sustained speed of almost 1000Mbps.

In other words, the net rate of a wired connection is very close to its ceiling speed. The wires inside a network cable are shielded from the elements and work unhindered.

Furthermore, in a router (or switch), the network ports don’t share the bandwidth. Each port delivers its total rated bandwidth even when all ports are active. So, if you copy data from one Gigabit device to another, the speed between them is generally 1Gbps.

The Wi-Fi bandwidth of the band, as mentioned above, is shared between the number of connected devices.

But we can’t always connect via wires. We need Wi-Fi for our mobile devices, bringing us to the first Tri-band content: The additional 5GHz band.

The additional 5GHz band

A Wi-Fi band generally has multiple channels — the number changes depending on how wide the channels are. But in any case, when a band is working using a particular channel, the rest of its channels are not used.

To overcome that and make use of more channels simultaneously in the wider 5GHz band, in 2014, chip makers decided to split the 5GHz frequency into two separate “bands”, each with its channel group — upper channels and lower channels.

And with that, we have the first concept of Tri-band broadcasters. Let’s call this concept “traditional” to distinguish it from the new Tri-band concept I will mention shortly.

So, a traditional Tri-band broadcaster includes a 2.4Ghz band and two 5GHz bands — that’s 2.4GHz + 5GHz + 5GHz. It’s a cheat way for the router to operate two 5GHz channels simultaneously out of the 5GHz spectrum.

On paper, a Tri-band broadcaster has double the bandwidth on the 5GHz frequency compared to a dual-band (2.4GHz + 5GHz) router. But things get complicated. Let’s look closely at Wi-Fi channels, especially on the 5GHz band.

5GHz band: Channels allocation, DFS vs Non-DFS

A Dual-band Wi-Fi broadcaster (2.4GHz + 5GHz) has two distinctive sets of channels. One belongs to the 2.4GHz band and the other to the 5GHz band.

In the US, the 2.4 GHz band includes 11 usable 20MHz channels (from 1 to 11) and has been that way since the birth of Wi-Fi. Things are simple in this band.

On the 5GHz frequency, things are complex — we have DFS and regular (non-DFS) channels. (On top of that, the last 5.9GHz portion of the band was reserved for other applications until late 2022 — more in this post on UNII-4.)

Here is the breakdown of the channels on the 5GHz frequency band at their narrowest form (20MHz):

1. The lower part of the spectrum includes channels: 36, 40, 44, and 48.
2. The upper part includes channels: 149, 153, 161, and 165.
3. In between the two, we have the following DFS channels: 52, 56, 60, 64, 100, 104, 108, 112, 116, 120, 124, 128, 132, 136, 140, and 144. (Channels from 68 to 96 are generally reserved exclusively for Doppler RADAR.)

In a dual-band (2.4GHz + 5GHz) broadcaster, the 5GHz band gets all the channels above (#1, #2). It’ll also get #3 if the broadcaster supports DFS.

In a traditional Tri-band broadcaster (2.4GHz + 5GHz + 5GHz), the first 5GHz band (5GHz-1) will get the lower channels (#1), and the 2nd 5GHz band (5GHz-2) gets the upper channels (#2).

If the broadcaster support DFS then the 5GHz-1 gets up to channel 64, and the rest (100 and up) goes to 5GHz-2. If it supports the new 5.9GHz portion of the 5GHz spectrum generally has three additional channels to its upper part, including 169, 173, and 177.

The splitting of the 5GHz spectrum ensures that the two narrower bands (5GHz-1 and 5GHz-2) do not overlap each other.

As a result, while the total bandwidth of the 5GHz spectrum remains the same in a traditional Tri-band broadcaster, we have the option of using two portions of this band simultaneously.

However, each portion (5GHz-1 or 5GHz-2) has fewer channels to choose from, making it harder for them to use the 80MHz or 160MHz channel widths. Physically, the channel-width options are now more limited than when the entire 5GHz spectrum is used as a single band.

Still, on paper, a traditional Tri-band broadcaster supposedly has double the bandwidth on the 5GHz frequency compared to a dual-band router of the same grade.

And networking vendors love this. A higher number means a better marketing tool. And then comes Wi-Fi 6E with its new Tri-band concept.

Tri-band with Wi-Fi 6E (2.4GHz + 5GHz + 6GHz): It’s the new Dual-band

In early 2021 the first Wi-Fi 6E routers came into existence. This new Wi-Fi standard extends Wi-Fi 6 and has a brand-new 6GHz frequency band.

And just like the move from single band to dual-band that took place more than a decade ago, now we’re doing the same, except it is a move from Dual-band to Tri-band, as a necessity.

A Wi-Fi 6E device must have all three bands (2.4GHz + 5GHz + 6GHz) to be compatible with all Wi-Fi devices, new and old. And that’s great, except it makes the Tri-band notion confusing.

That’s because traditionally, a Tri-band router (be it a Wi-Fi 5 or Wi-Fi 6 one) has an additional 5GHz band only to add extra bandwidth. It does not need this band to work with existing devices.

Still, the hardware vendors jumped on the chance to promote new hardware as “ideal” for a wireless mesh system by picking and choosing the range of the 5GHz band and the signal strength of the 6GHz band. (You can’t have both.)

In reality, in a fully wireless configuration, all existing Tri-band Wi-Fi 6E mesh Wi-Fi systems proved in my testing to be inferior to traditional Tri-band counterparts in a wireless setup because they didn’t have a dedicated backhaul band.

And that’s where the reason Quad-band came into existence.

Quad-band Wi-Fi 6E (2.4GHz + 5GHz + 5GHz + 6GHz): It’s the same as the original Tri-band

In late 2021, Netgear introduced its first Wi-Fi 6E mesh system, the Orbi RBKE960 series. It’s also the first Quad-band system on the market.

Quad-band how?

Well, the company used the original Tri-band concept — again, that’s 2.4GHz + 5GHz + 5GHz — and added a new 6GHz band.

As a result, the RBKE960 proved to be one of the best among Wi-Fi 6E mesh systems in my testing in a fully wireless configuration. You can still use a 5GHz band (the 5GHz-2) as the dedicated backhaul band, just like any Tri-band Orbi set, plus the support for the 6GHz band on the fronthaul.

But that also means Quad-band is essentially the new traditional Tri-band since the extra 5GHz band is where it matters.

And in a wireless mesh setup, this Quad-band configuration has the same drawbacks as any Tri-band mesh system, namely the fluctuating and relatively slow backhauling, which depends on how you arrange the hardware.

And that brings us back to our endearing original bandwidth idea: Dual-band vs Tri-band.

Dual-band (2.4GHz + 5GHz) vs traditional Tri-band (2.4GHz + 5GHz + 5GHz): The reality

As far as I know, the first original Tri-band router is the Netgear R8000 Nighthawk X6 that came out in 2014. I remember reviewing it in my past life and having difficulty figuring out how to demonstrate the need for the second 5GHz band.

Frustrated yet curious, I got one for my personal use and ended up putting it in storage without ever figuring out the advantages of the additional 5GHz band — in a single router. I still have that router today, in 2023.

And that’s just the way it is. In real-world usage, you’ll probably see no difference between Dual-band vs Tri-band in standalone Wi-Fi routers or even in a mesh system with wired backhaul.

That’s because, in any real-world environment, it’s always hard for a broadcaster to find the best channel to broadcast in real time, and having more bands (two instead of one) might make the matter worse.

And on the receiving end, clients generally don’t know which is the “better” band to use. So one band might be full while the other is empty.

But even if everything works as intended, chances are you don’t have that many active clients to make the notion of Tri-band meaning anyway.

Let’s dig a bit deeper.

Connected clients vs active clients

As mentioned above, a router shares its Wi-Fi bandwidth between active devices. You can have hundreds of connected clients, but only the active ones count.

The faster a connection is, the shorter a client remains active — it needs less time to finish transmitting the same amount of information.

For example, as you’re reading this, the connection of your computer (or mobile device) is likely no longer active since it has fully downloaded the webpage. So, in a typical home, chances are you’ll have just a few active clients at any time.

And even when you have many active clients, how taxing they are on the Wi-Fi pipe also depends on their tier of Wi-Fi, the application they use, and the Internet speed.

Wi-Fi tiers

The numbers I mentioned in the RT-AX89X example above applied only to top-tier Wi-Fi 6 clients. In most homes, though, chances are you’ll use clients of different Wi-Fi speed grades and standards.

For example, if you use a 2×2 Wi-Fi 5 client, its speed already caps at 867 Mbps, even when it’s the only connected client. If you use 2×2 Wi-Fi 4 devices, this number is now 450 Mbps at most. So on and so forth. Also, some clients use the 2.4GHz band and put no load on the 5GHz frequency.

So, not all active clients use the max amount of bandwidth available at the router’s end, even when working at capacity.

Applications

And Wi-Fi clients tend not to work at capacity. That’s because most applications only need a certain amount of bandwidth. You can make more available to them, but that won’t translate into a better user experience. It’s the law of diminishing returns.

Take movie streaming, for example. A 4K stream requires 25 Mbps and won’t use more than that.

So the RT-AX89X router’s 5GHz band alone can theoretically handle some 200 Wi-Fi concurrent clients streaming 4K content. Add another few dozen clients on the 2.4GHz band.

Internet speed

The broadband speed is likely the main factor that renders tri-band overkill. That’s because we use Wi-Fi mainly as a bridge to the Internet.

And since Wi-Fi and the Internet are two different things, faster Wi-Fi doesn’t necessarily translate into speedier Internet access. (When you get Gigabit-class Internet, the faster-the-connection-the-shorter-the-active-time rule mentioned above applies.)

Click the Go button below and do a test right now, and you’ll get an idea of how fast your Internet is. (Check out this post on how I conduct Wi-Fi and Internet testing.)

⏱️ Dong Knows Tech custom Speed Test transfers data between your device and an Ookla test server

Let’s say your broadband is 500Mbps, which is quite good. When you have ten Wi-Fi clients accessing the Internet simultaneously, using the same application, they will be allotted 50Mbps each.

And even if you have just one client, 500Mbps is still lower than how fast Wi-Fi can be in most cases. So, no matter how much bandwidth you add to your Wi-Fi, you can’t access the Internet any faster.

The point is, chances are the broadband connection will be used up way before you have to worry about your local Wi-Fi’s speed. Consequently, getting more Wi-Fi bandwidth doesn’t do anything other than make you a bit poorer.

When the extra 5GHz band is useful

There are a few instances where an extra 5GHz band — that’s Tri-band (Wi-Fi 5 / Wi-Fi 6) or Quad-band (Wi-Fi 6E) — makes sense.

First, you need to have many 5GHz clients to consider using this type of broadcaster. And then, make sure you have at least one of the following to make the investment worthwhile.

Wireless mesh setup

Wireless mesh is by far the best use of the extra 5GHz band. That’s when you use multiple hardware broadcasters that link to one another wirelessly — no network cable is involved.

In this case, generally, a Tri-band (or Quad-band Wi-Fi 6E) system will dedicate one of the two 5GHz bands as the dedicated backhaul, which has the sole job of linking the broadcasters, leaving the other bands — 5GHz + 2.4GHz + 6GHz (when applicable) — free to serve clients. Among other things, this setup helps reduce or even eliminate signal loss.

Note that using a network cable to link broadcasters is the best way to get a non-compromising mesh system. In this case, you only need to use dual-band, or Tri-band Wi-Fi 6E, broadcasters.

Getting a system with an additional 5GHz band and using it for wired backhauls can be wasteful since you still might not use its extra 5GHz band. That’s the case with all Netgear Orbi.

Network segmenting: Compatibility, bandwidth, VR, etc.

Having many bands always helps with segmenting your network.

You can set the two 5GHz bands for two groups of clients. Apart from managing the broadcaster’s bandwidth effectively, that also helps with compatibility and other connection issues.

A router with an additional 5GHz band is also helpful if you have an extensive network that uses Wi-Fi instead of wired connections for local tasks. It allows for more local bandwidth.

These include network backups, file sharing, and photo/video editing. Another thing is if you use Wi-Fi to connect virtual reality headsets, a dedicated 5GHz (or 6GHz) band will help tremendously.

The takeaway

Generally, you don’t need any additional Wi-Fi band in a standalone broadcaster or a mesh system with wired backhauling. Sometimes, this extra band helps, but it is still not a must-have. Generally, broadcasters with a band for each frequency always suffice.

On the other hand, I don’t see any instance having more bands — that use different parts of the wireless spectrum — would hurt.

So, in the end, it comes down to cash. If you can afford it, proceed with a router with the most bands. Once in a while, it’s nice to turn things up to eleven.