DOCSIS 3.0, 3.1, 4.0: What's the Real Difference?

If you have cable internet, then you're using DOCSIS technology. DOCSIS, which stands for data over cable service interface specifications, is a standard that defines how your modem relays cable internet signals going to and from your home. If you have cable internet, whether from Cox, Spectrum, Xfinity or one of many regional cable internet providers, you're using a DOCSIS-compliant modem. 

Modern cable modems are compliant with DOCSIS 3.0 or 3.1, with more and more internet service providers recommending DOCSIS 3.1 modems. Specifications for DOCSIS 4.0 have been released, but DOCSIS 4.0 modems aren't yet available for retail purchase.

If you’re shopping for a new cable internet modem, you’ll have the choice of DOCSIS 3.0 or 3.1. As the numbers suggest, the two modem versions are similar, but I recommend opting for DOCSIS 3.1 if you don't want to wait for a new 4.0 modem.

What are the differences between DOCSIS 3.0, 3.1 and 4.0?

Despite the simple one-tenth difference in versions, DOCSIS 3.0 and 3.1 modems vary significantly in performance, pricing and availability. DOCSIS 4.0 would imply a bigger jump in performance, but the improvement largely has to do with upstream capacity. Here's a quick look at the advantages of each.

DOCSIS 3.0 modem advantages

• Price: DOCSIS 3.0 cable modems are generally cheaper than their 3.1 counterparts. 
• Availability: You're likely to have more options, including used or refurbished devices, when shopping for a DOCSIS 3.0 modem.

DOCSIS 3.1 modem advantages

• Speed: DOCSIS 3.1 cable modems support faster speeds than DOCSIS 3.0 modems and are thus better suited for high-speed plans, especially those with gig speeds or higher.
• Security: DOCSIS 3.1 modems may offer better online security than 3.0 models, especially if you purchase a modem-router combo device.

DOCSIS 4.0 modem advantages

• Upload speeds: DOCSIS 4.0 is designed to "significantly increase upstream capacity," according to CableLabs, the organization that sets and tests DOCSIS specifications.
• Future proof: DOCSIS 3.1 is the current standard, but 3.0 is still in use, nearly two decades after its introduction in 2006. It’s safe to assume that 4.0 modems will be useful for many years to come.

DOCSIS 3.0, 3.1 and 4.0 specifications

The most significant difference between DOCSIS 3.0 and 3.1 is that the latter can support download speeds 10 times faster than DOCSIS 3.0, up to 10Gbps. DOCSIS 4.0 also supports downloads up to 10Gbps but is capable of significantly faster uploads, up to 6Gbps. The symmetrical, or close, download and upload speed capacity brings cable internet closer to matching the speed potential of fiber-optic internet service.

DOCSIS 4.0 could pave the way for faster cable plans with faster upload speeds

Most cable providers already offer a gigabit plan with maximum speeds of around 940 or 1,000 megabits per second. Astound, Cox, Xfinity and select other cable providers offer download speeds above 1,000Mbps. With DOCSIS 4.0 technology, cable providers can offer even faster speeds using their current cable/fiber hybrid infrastructure.

The DOCSIS 4.0 modem notably allows for much quicker upload speeds, which cable providers are sorely lacking. According to CableLabs, DOCSIS 4.0 allows for "an increase in upstream capacity and more options for operators to increase downstream capacities."

Still, DOCSIS 3.1 is the current standard for high-speed cable internet

If you choose speeds above 1 gig and rent your equipment, you'll receive a modem-router combo that comes with DOCSIS 3.1 built-in, so you don't have to worry about your modem's specifications. Otherwise, if you choose to use your own equipment, you'll want to spend a little extra for a DOCSIS 3.1 modem to take full advantage of the plan's speed potential.

What if I don't need gig and multi-gigabit speeds?

The speed potential of DOCSIS 3.1 and 4.0 is impressive, but unless you've got a high-speed plan, that may not matter. Suppose your selected plan comes with speeds up to 200Mbps. If you rent from your provider, the modem included with your equipment may be a DOCSIS 3.0 model, which can support your internet connection just fine.

If you use your own modem, you probably won't see much of a performance improvement, if any, by purchasing a DOCSIS 3.1 device over a DOCSIS 3.0 one. Considering the price difference and available options between the two, you'd be better off opting for DOCSIS 3.0 on lower-tiered internet plans.

DOCSIS 3.0 has more, cheaper options

DOCSIS 3.0 is the cheaper option when shopping for a modem or modem-router combo. New DOCSIS 3.0 modems can cost between $50 and $150 depending on the device you choose and the source you buy from, but you may be able to score a used device for less than $50. On the other hand, DOCSIS 3.1 modems can easily cost $150 to $250 or higher.

Manufacturers like Arris, Asus, Netgear and Motorola have made DOCSIS 3.0 modems for years. These manufacturers make DOCSIS 3.1 modems as well, but you'll likely have fewer options than you would if you were shopping for a DOCSIS 3.0 modem.

Is DOCSIS 3.0 outdated?

In terms of the latest technology shaping how we get online, yes, DOCSIS 3.0 is sorely outdated. With more and more ISPs rolling out multi-gig plans and the overall trend of heavier internet usage in recent years, according to Open Vault, a DOCSIS 3.0 modem will not support the faster speeds many internet users are turning to. If you don't have a need for speed, you'll most likely be fine with a DOCSIS 3.0 modem, especially if you're trying to save money by avoiding an upgrade.

Still, nearly all ISPs support DOCSIS 3.1 and often recommend DOCSIS 3.1 to get the most out of your internet connection.

DOCSIS 3.1 is more secure and better for long-term use

Any major internet protocol update, like the transition from DOCSIS 3.0 to 3.1, will include improved security features. This typically comes with enhanced encryption, so a DOCSIS 3.1 modem will presumably be better equipped to secure your information. Additionally, the best router and modem combos equipped with DOCSIS 3.1 will also include WPA3, a more advanced router security feature than older modem routers that may come with DOCSIS 3.0 and WPA2. 

DOCSIS 3.0 was released in 2006, and DOCSIS 3.1 arrived in 2013, which is a long time in the tech world -- long enough for initial security measures to become outdated. Modem manufacturers and ISPs release regular security updates to keep your equipment safe. Still, I would recommend additional security software or a good VPN to help boost your online security, especially when using a DOCSIS 3.0 modem.

Considering the increase in home internet speeds and the need for up-to-date security, DOCSIS 3.1 is well on its way to fully replacing DOCSIS 3.0. It hasn't entirely done so, mainly because slower, cheaper cable internet plans can still get by with DOCSIS 3.0 technology.

Coming soon: DOCSIS 4.0

DOCSIS 4.0 technology is on the verge of improving cable internet service, but it's not here just yet. Xfinity is the only major cable internet provider to have begun rolling out DOCSIS 4.0, but only to select service areas in Atlanta, Georgia; Colorado Springs, Colorado and Philadelphia, Pennsylvania.

Unfortunately, if you want to get ahead of the game and purchase a DOCSIS 4.0 modem, you're out of luck. There are currently no DOCSIS 4.0 modems available for retail purchase, at least none I could find from a trusted source.

Why choose one DOCSIS modem over the other?

Since DOCSIS 4.0 modems aren't available yet, your choice of a new or used device will come down to 3.0 or 3.1 versions. If you're content with a low- or mid-tier cable internet plan, a DOCSIS 3.0 modem will likely meet all your needs and come at a lower price than a DOCSIS 3.1 device.

If you sign up for faster speeds, especially those approaching or surpassing 1Gbps, or simply want a device you know you can use for years, a DOCSIS 3.1 modem is the way to go. You'll have to pay more for a DOCSIS 3.1 modem, but chances are you're also paying a premium for those faster speeds, so you might as well equip your home with a device to let you enjoy them.