By Joel Santo Domingo and Thorin Klosowski
This post was done in partnership with Wirecutter. When readers choose to buy Wirecutter's independently chosen editorial picks, Wirecutter and Engadget may earn affiliate commission. Read the full guide to cable modems.
After researching nearly 100 cable modems over the past five years, we recommend the Netgear CM600 if you have cable Internet and you want to stop paying your Internet service provider a separate modem rental fee. You can recoup the cost of the modem in as little as nine months—and then start saving up to $10 each month.
The CM600 is reliable, supports the fastest Internet speeds available to the vast majority of Americans, and it's compatible with just about every non-gigabit plan from every cable Internet service provider in the US—including Comcast Xfinity, Spectrum (formerly Time Warner, Charter, and Bright House), Cox, Suddenlink, Cable One, and WOW—which gives you the flexibility to switch providers if you move or switch ISPs. The CM600 works well for plans up to 600 megabits per second, because it's a DOCSIS 3.0 modem that can handle 24 downstream channels and eight upstream channels. The biggest downside is that, while the CM600 has positive reviews from owners, it comes with only a one-year warranty, while most modems come with a two-year warranty.
The Motorola MB7621 is a 24×8 DOCSIS 3.0 modem that supports the same performance levels as the Netgear CM600. The MB7621 is less expensive and comes with a two-year warranty, a year longer than the CM600's coverage. But it doesn't appear on quite as many ISP approved modem lists as the Netgear modems; Cable One, Cox, and Comcast Xfinity all have the MB7621 on their online approved lists, but you'll have to call Spectrum and WOW to make sure it will work on their networks and what speeds it will support. The MB7621 doesn't have quite as large a pool of reviews, but what people have to say is very positive. It's a great choice if your ISP supports it.
America's average Internet speeds measure well below 100 Mbps, ranging from the low 20s to figures approaching 70 Mbps, depending on which survey you pick. If your plan is in that range and you don't intend to upgrade beyond 300 Mbps anytime soon, we recommend the Netgear CM500. The CM500 matches the ISP compatibility of the pricier CM600, but its maximum download and upload speeds are lower (300 Mbps on the CM500 versus 600 Mbps on the CM600, though Suddenlink certifies it for 500 Mbps speeds). The CM500 has a good reputation for reliability, but like the CM600 it comes with only a one-year warranty.
(We recommend 16×4 modems like the CM500 even if your plan would work with a slower modem, because ISPs are dropping support for 8×4 modems. You'd save barely any money up front and have to replace your modem years earlier, so we don't recommend it.)
If you already have a gigabit Internet plan and your ISP allows you to use your own modem, the Motorola MB8600 is the best of the three DOCSIS 3.1 modems that are widely available right now because of its relatively low price and its two-year warranty. Though it's overkill for almost everyone, you'll need a DOCSIS 3.1 modem to guarantee gigabit speeds from most cable ISPs, and the MB8600 is also compatible with gigabit Internet on networks that still use the DOCSIS 3.0 standard, for example Cable One supports both DOCSIS 3.0 (32x8) and DOCSIS 3.1 modems for its GigaOne service.
Don't get a gigabit modem unless you already have gigabit service or know it's available. The added expense of the DOCSIS 3.1 modems isn't worth it until you're on one of these new (and pricey) plans—especially since your ISP may roll out gigabit over fiber rather than cable. And they may not even let you bring your own modem once they do roll out gigabit service.
Modem compatibility list, updated October 2018
Some content has been removed for formatting reasons, please view the original article for the best reading experience.*Suddenlink told us that all DOCSIS 3.0 modems will work with the company's service. But you should call Suddenlink to verify compatibility before purchasing.
Why you should trust us
Before joining Wirecutter, Joel Santo Domingo tested and has written about PCs, networking products, and personal tech at PCMag and PC Magazine for more than 17 years. Prior to writing for a living, Joel was an IT tech and sysadmin for small, medium, and large companies.
Thorin Klosowski spent almost six years at Lifehacker writing about hardware, software, and every other facet of technology.
Who this is for
You should buy a cable modem if you're currently paying a fee to rent one from your ISP. Most ISPs charge $10 a month to rent a modem—that's $120 a year, every year, on top of what you're already paying for Internet access. (Altice and Spectrum include the modem-rental cost in their current Internet plans, but if you haven't changed your plan in a few years, you may still be paying a rental fee; give Altice or Spectrum a call to see what your current options are.) Unless you have gigabit-speed Internet, you can expect to pay around $60 to $90 for a modem, which means you'll save money in less than a year.
Many ISPs rent out modems that double as wireless routers, which means that if you replace your rental modem with one you bought, you may also need to buy a wireless router if you want Wi-Fi in your house (if you're not sure what the difference is between a router and a cable modem, we have a guide for that.) Our favorite Wi-Fi router currently sells for less than $200, but you can find a decent one for around $100. That puts your total up-front cost as low as $160, which means it pays for itself in a year and a half. Your modem and router should last you at least a few years if not more, so even if you go for the more expensive option, you'll still come out on top. ISP-supplied modem-router combos tend to have bare-minimum feature lists and poor Wi-Fi range, while standalone routers have added antennas for better coverage, more parental control settings, and other nice-to-have features like guest networks and VPN servers.
Some content has been removed for formatting reasons, please view the original article for the best reading experience.(Legacy plans from Optimum, Time Warner Cable, or Charter may include a modem-rental fee depending on who your ISP was before the merger. Most current Spectrum plans do not have a separate fee. Fees current as of September 28, 2018.)
Don't buy a cable modem if you're on DSL or fiber; those technologies use different standards and connectors. Verizon Fios lets you buy your own modem-router combo, but you have only a single choice, and it's identical to the equipment they rent to you.
Also don't buy one if you use your cable provider for telephone service: The models we cover here don't have phone ports. If you need one that does, check to see which "telephony" or eMTA modems your ISP supports, and if the company allows you to buy your own. Comcast Xfinity's webpage has a checkbox so you can determine which approved modems are voice/telephone enabled, and Cox has a list of approved modems that are compatible with their voice services. Cable One notes that it only supports a couple of Arris modems (including the one it leases to you) for voice service on its support site, while WOW only supports its leased WOW! Advanced Modem for voice. The telephony modems you can buy are also more expensive than regular cable modems.
When to replace your old modem
You should get a new modem if yours doesn't support DOCSIS 3.0, the most widespread iteration of the Data Over Cable Service Interface Specification, which governs how cable operators deliver high-speed cable Internet. If you've had your modem for four or five years, give the model name a quick Google search; you might still be using a modem that supports only DOCSIS 2.0, in which case it's time to upgrade. But if you already own a DOCSIS 3.0 cable modem that supports your Internet plan's top rates, don't buy a more powerful (and more expensive) cable modem for the sake of future-proofing.
The first two versions of DOCSIS used only one downstream channel (for downloading data) and one upstream channel (for uploading data). DOCSIS 3.0 allows modems to bond multiple channels into a single data stream, giving you 38 Mbps per channel. Since those channels can combine, you can theoretically get up to 606 Mbps with a 16-channel modem and up to 1.2 gigabit per second with a 32-channel modem.
A modem's maximum speed, as the manufacturer lists it, doesn't mean all that much. Most ISPs limit 16×4 modems to around 300 Mbps even though in theory they can hit 600-plus Mbps. Most currently available 24×8 or 32×8 modems max out at 600 Mbps or 1 Gbps, respectively. If you buy a 1 Gbps modem but pay for only 300 Mbps service, your download speeds are still limited to 300 Mbps. Unless you're on a very congested network with constant slowdowns, you likely won't notice a huge difference from added channels on slower speed tiers.