Roborock S4 Max robot vacuum review

While there are plenty of budget-busting robot vacuums ready to do your bidding, finding one like the Roborock S4 Max, which combines performance and affordability, is rare. It gets the job down smartly and efficiently-- without cleaning out your wallet. 

Plenty of robot vacuums are filled to the dustbin’s brim with features and add-ons that don’t always work well. In the quest to cram in more and more features, some robot manufacturers have forgotten the most important feature of all: actual cleaning performance. In our Roborock S4 Max review, we found a vacuum that works well and has useful, modern features. With fast mapping, single room cleaning, and automatic carpet detection, the $429 S4 Max strikes the right balance of performance, features, and cost. All of that has earned a spot at the top of our best robot vacuums list.

• Best robot vacuums for pet hair
• What you need to know: Robot vacuum buying guide
• Best robot mops

The Roborock S4 Max has also won big in the Tom's Guide Awards 2021 Smart Home Devices categories, taking home the Best robot vacuum overall award! Check out the full smart home devices awards for more winners and recommended runners-up.

Roborock S4 Max: Price and availability

The Roborock S4 Max was released in September 2020 and is available at Amazon for $429. Automatic carpet detection and a larger dustbin differentiate it from the older Roborock S4. If you’re looking for advanced features, the $749 Roborock S6 MaxV adds onboard cameras for object detection and mopping capabilities.

Roborock S4 Max: Design

The Roborock S4 Max is an attractive, but understated-looking vacuum. As one might expect, the Roborock S4 Max bears a striking resemblance to its feature-packed bit brother, the Roborock S6 MaxV. The S4 Max trades in shiny black plastic for matte black plastic with tasteful matte silver trim around the top of the bot. Measuring 13.5 inches in diameter, it’s 0.4 inches smaller than the S6 MaxV, but it’s really only noticeable when the two vacuums are side by side. Both are 3.8 inches high at their vertical bumper, a.k.a the disc that juts out from the top of the bot. The rear of the S4 Max is clad in more matte black plastic, speckled with air exhaust holes.

There are only two rubberized buttons atop the Roborock S4 Max: A power button and a home button. Press and hold the power button to turn it on or off. A quick press activates a cleaning. Somewhat confusingly, a long press of the home button, which looks like a stick house, activates spot cleaning mode, while a short press sends it back to the dock. The Roborock S6 MaxV has a dedicated spot cleaning button, which makes a lot more sense.

The Roborock S4 Max has a clean, unencumbered look as it glides across your floor, thanks to a flip up hood that conceals its dustbin, Wi-Fi indicator light, and cleaning tool. In general, I prefer this dustbin placement. Not only is it easier to remove, but it’s also easier to see when your dustbin is nearing capacity. The dustbin on the S4 Max pulls out via a small handle, keeping the sneezy stuff just a little bit further from you. 

The underside of the Roborock S4 Max features two chunky rubberized wheels on either side of the brush roll and an omnidirectional caster wheel at the front of the bot. A five-spoke brush with rubber “bristles” sits to the side. The spokes are angled downward to aid in catching debris and pushing it towards the brush roll. 

There’s nothing special about the dock included with the Roborock S4 Max. It’s identical to the one included with the Roborock S6 Max. It’s small and unobtrusive, which looks good in a living room. However, the vacuum pushed it around a few times when trying to dock, despite the rubber grips on the bottom. Roborock includes a strip of double-sided tape to affix the dock to your floor, but I’d rather take my chances with an undocked robot vacuum than adhesive residue on a hardwood floor.

Roborock S4 Max: Cleaning performance

There have been a lot of robot vacuums lately that pile on features and extras but forget the most important part—solid vacuuming performance. The Roborock S4 Max is not one of them. It earned an overall score of 96.25, on a par with the much more expensive iRobot Roomba s9 and better than its (also more expensive) sibling the Roborock S6 MaxV (90.56). It also topped our previous top robot vacuum, the Shark Ion R85, by two points, and bested the Neato D4.

When it came to picking up cereal, the Roborock S4 Max was nearly perfect, earning an average pickup rate of 98.38, roughly one Cheerio less than the S6 MaxV’s 98.9 average, and better than the Roomba s9’s 92.5 average. The Shark Ion R85 earned a perfect cereal pick rate.

*Same test performed in a larger 15’ x 15’ area.

The only stumble for the Roborock S4 Max was picking up dog hair. Though it technically picked up all of the dog hair on hardwood, the vast majority of it was caught up in the brush roll and not in the dustbin. Only 8.5% of hair made it into the dustbin; the rest was clumped around the brush roll and suction inlet. Still, the dog hair was picked up and removed from the surface, so it counted. 

*Same test performed in a larger 15’ x 15’ area.

On our carpet tests, the Roborock S4 Max offered similar, but better performance than the Roborock S6 MaxV. It matched or surpassed the Shark Ion R85 when picking up cereal and kitty litter, though stumbled a bit on dog hair. And while it didn’t quite surpass the iRobot Roomba s9 when cleaning up kitty litter and pet hair on carpet, the $429 vacuum sure came close, cleaning up 95% of the litter and 88% of the dog hair. Unlike on hardwood, the vast majority of hair ended up in the S4’s bin, and didn’t get stuck on the brush roll.

*Same test performed in a larger 15’ x 15’ area.

Roborock S4 Max: Setup, app, and mapping

Connecting the Roborock S4 Max to our home Wi-Fi and the Roborock app (Android and iOS) was quick and relatively easy. Like most app-connected robot vacuums, the app walks you through the process. The S4 faltered and didn’t connect on the first try, but connected quickly on the second.

The Roborock app is intuitive and mostly works well. The main screen for the vacuum displays the area cleaned, the battery level, and the cleaning time above the current map. I liked that the app also keeps track of the S4 Max, showing both its current location and the path where it cleaned most recently.

You can choose from four cleaning modes within the app: Quiet, Balanced, Turbo, and Max. In addition to the cleaning modes, there is a lot of customization within the app settings. Some options, like automatically increasing suction when carpet is detected, struck me as no brainers. Why wouldn’t you want that functionality enabled out of the box? Another option is setting a do not disturb time frame, which keeps the vac from cleaning, lowers voice prompt volume, and dims the indicator light. There’s also an option to choose your preferred unit of measurement-- feet or meters-- though we noticed our preference for feet didn’t completely carry over to the zone measurements on the map.

One option I wish was included on the main settings page: Map saving. Instead, you have to tap the Edit Map button. I missed turning this on the first time and lost the initial map the Roborock S4 Max created. This is also where you enable single-story or multi-story mapping, where up to four maps can be saved. It’s far less than the Roomba i7 and Roomba s9’s ten maps, but it’s more than enough for a two-story home and basement. 

The Roborock S4 Max uses LiDAR navigation to find its way, which enables a much faster mapping experience. Like the Roborock S6 MaxV and the Ecovacs Deebot Ozmo T8, the S4 Max created an accurate map on its first run. By comparison, the iRobot Roomba s9 and Roomba i7 use vSLAM and took more than one run to create a complete map. 

Once the first floor map was completed and saved, I was able to create rooms, no-go zones and invisible walls. In theory, creating room divisions should be easy, but I ran into a “Reset failed” error when I attempted to divide my kitchen and dining room. Both Roborock’s support forum and Reddit suggested the error was caused by a room having more than one entry point. Since I had no problem making a dividing line for my bathroom, this seems likely. The solution was to create smaller divisions following along walls and then merge those together. Thankfully, this method worked, but it was more hassle than I wanted from a vacuum. 

Once rooms are set up, you’re able to create custom labels for them instead of having to choose from a pre-populated list. While the labels are helpful, they’re not necessary for room-specific cleaning. From this point, you’re able to clean individual rooms. What’s extra cool is that you can set specific times to clean each room, such as cleaning the kitchen at 9pm each night after dinner.

Just want to clean a certain area quickly? Select Zone cleaning, which allows you to draw a box around the area you want to clean. It gives you more control and the option for a larger cleaning area than the onboard spot cleaning.

The Roborock S4 Max was very respectful of no go zones and invisible walls I created within the app. It made a sharp turn as it “hit” the invisible wall I drew through my kitchen and dining room. Likewise, it was respectful of the no go zone around my kitchen sink and never once crossed the boundary. This adherence to invisible boundaries was displayed in the app as well, allowing us to double check the robot’s work. 

Roborock S4 Max review: Verdict

Do one thing and do it well. That’s the best way to sum up the Roborock S4 Max. Instead of trying to tack on a mopping plate or other features that drive up the price but rarely enhance performance, the Roborock S4 Max just works well. While it's $100 more than the Neato D4, the S4 Max offers better performance and it’s able to create more than one map. 

The older Shark Ion R85 doesn’t offer mapping or automatic carpet detection and can’t really compete with more modern robot vacuums. The mapping on the S4 Max is coherent and fast—even in spite of the hiccup I encountered—and the robot does as it’s told. If you want a robot vacuum with excellent cleaning prowess and advanced features like single room cleaning and scheduling, the $429 S4 Max will serve you well.