I’ve been busy testing auto-empty robot vacuums the past few weeks, and among those are the Roomba I3+, I6+, and S9+. These three variants represent every tier in the iRobot self-emptying product lineup.
When iRobot released the Roomba I7+, this innovation disrupted the industry into coming up with their own versions.
I’d say that Roomba’s auto-empty design is still one of the best, with the more stable ramp versus vertical ports utilized by other brands.
Which of the three is the best option? I’ve compiled all the test results to decipher which of the three is worthy of your consideration.
[toc]Quick overview of the I3 vs. I3+ vs. I6+ vs. I7 vs. I7+ vs. S9 vs. S9+
Let’s quickly look at the Roomba auto-empty options’ specs, including the I3, I3+, I4+, I6+, I7, I7+, S9, and S9+.
Note: I’ve only tested the I3+, I6+, and S9+, so I could only provide test result numbers for these variants. But realize the I4 and I7 are similar to the I3 and I7, respectively, with product specifications, color, and accessory variations.
I used 100 grams of fine sand and rub it on mid-pile carpet and run the robots for around 5 minutes to see how much it picks up.
Noise experiments are done using a sound meter from a few feet away.
Roomba I3
- Clean base Station: No
- Navigation: Neat Rows
- Map saving: No
- Keep out zones: No
- Selective Room cleaning: No
- Recharge & Resume: Yes
- Rubber extractors: Yes
- Dustbin capacity: 500ml
- Side brush: One
- Battery: 1800 mAh Li-ion
- Run time: 75 minutes
Roomba I3+
- Airflow: 7.27 CFM
- Deep Cleaning: 84.7%
- Clean base Station: Yes
- Navigation: Neat Rows
- Map saving: No
- Keep out zones: No
- Selective Room cleaning: No
- Recharge & Resume: No
- Rubber extractors: Yes
- Dustbin capacity: 400ml
- Side brush: One
- Battery: 1800 mAh Li-ion
- Run time: 75 minutes
- Noise: 64.9 dB
Roomba I4+
- Clean base Station: No
- Navigation: Neat Rows
- Map saving: No
- Keep out zones: No
- Selective Room cleaning: No
- Recharge & Resume: Yes
- Rubber extractors: Yes
- Dustbin capacity: 500ml
- Side brush: One
- Battery: 1800 mAh Li-ion (w/ an option for a larger battery)
- Run time: 75 – 100 minutes (depending on sub-model)
Roomba I6+
- Airflow: 8.2 CFM
- Deep cleaning: 82.5%
- Clean base station: Yes
- Bag capacity: 2.5 liters (approx.)
- Navigation: Neat Rows
- Map saving: Yes
- Number of maps: 10
- Keep out zones: Yes
- Selective Room cleaning: Yes
- Recharge & Resume: Yes
- Rubber extractors: Yes
- Dustbin capacity: 400ml
- Side brush: One
- Battery: 1800 mAh Li-ion
- Run time: 75 minutes
- Noise: 64.9 dB
Roomba I7
- Clean base Station: No
- Navigation: Neat Rows
- Map saving: Yes
- Number of maps: 10
- Keep out zones: Yes
- Selective Room cleaning: Yes
- Recharge & Resume: Yes
- Rubber extractors: Yes
- Dustbin capacity: 400ml
- Side brush: One
- Battery: 1800 mAh Li-ion
- Run time: 75 minutes
Roomba I7+
- Clean base station: Yes
- Bag capacity: 2.5 liters (approx.)
- Navigation: Neat Rows
- Map saving: Yes
- Number of maps: 10
- Keep out zones: Yes
- Selective Room cleaning: Yes
- Recharge & Resume: Yes
- Rubber extractors: Yes
- Dustbin capacity: 400ml
- Side brush: One
- Battery: 1800 mAh Li-ion
- Run time: 75 minutes
Roomba S9
- Clean base Station: No
- Navigation: Neat Rows
- Map saving: Yes
- Number of maps: 10
- Keep out zones: Yes
- Selective Room cleaning: Yes
- Recharge & Resume: Yes
- Rubber extractors: Yes
- Dustbin capacity: 500ml
- Side brush: One
- Battery: 1800 mAh Li-ion
- Run time: 75 minutes
Roomba I9+
- Airflow: 25 CFM
- Deep cleaning: 93%
- Clean base station: Yes
- Bag capacity: 2.5 liters (approx.)
- Navigation: Neat Rows
- Map saving: Yes
- Number of maps: 10
- Keep out zones: Yes
- Selective Room cleaning: Yes
- Recharge & Resume: Yes
- Rubber extractors: Yes
- Dustbin capacity: 500ml
- Side brush: One
- Battery: 1800 mAh Li-ion
- Run time: 75 minutes
- Noise: 74.1 dB
Introduction to the Roomba I3+, I6+, and S9+
As I’ve said earlier, the Roomba I3, I6, and S9 represent iRobot’s different tiers in the self-emptying robot line.
iRobot was a pioneer in unveiling the Roomba I7, and soon afterward, other variants came out, like the I3, I4, I6, I7, and S9.
Please note that these sub-models, for example, the I4 are clones of other sub-variants of the I3. It will have similar features, specs, motor, and navigation. But I have not tested these products, so I cannot provide any results.
Entry-Level Option: Roomba I3+
The Roomba I3+ is their least expensive option, but with the “dumbest” navigation. iRobot calls it a smart navigating robot, capable of moving “neat rows,” meaning traverses in straight lines.
However, it lacks VSLAM or Visual SLAM, so it can’t save maps; thus, users won’t have access to features like keep-out zones or zoned cleaning.
This omission is why iRobot could bring the price down a tier below the I7 and S9.
The Roomba E5, I3, and I6 share the same basic framework: the same dimension, dustbin, and brush layout. But the I3 is better than the E5 with navigation as it moves in straight lines.
However, it lacks VSLAM, so it doesn’t have a top-mounted camera and SLAM. It cannot recognize landmarks or clean specific areas.
Smarter, Mid-Level Option: Roomba I6+
A more advanced option would be the Roomba I6+. Like I3+, it moves in neat rows, but this variant has a top-mounted camera and SLAM, unlocking advanced features like zoned cleaning not available in the I3.
Adding these wrinkles brings a lot of conveniences, but you’ll need to spend more.
Based on airflow tests, the I6+ has a tiny bit more than the I3, but it’s big enough to be a difference-maker.
The I3 and I6 are very close with cleaning tests (more details below), with the I6 being slightly better on surface debris pickup. Maybe the higher airflow is a factor why, but it’s very close to declaring an outright winner.
Best in Class Cleaning Performance: Roomba S9 +
Before unveiling the S9, all Roomba products feature a round frame with a three-pronged side brush and narrow extractors at the middle portion.
All that changed with the S9; iRobot revamped the design using a D-shape, similar to the Neato Botvac series.
These upgrades and the more potent motor aim to improve the S9’s performance.
The S9 plus extractors now span nearly the entire robot width, and the high airflow picks up cleaner than any other Roomba I’ve tested so far.
It has up to 25 CFM in the highest setting, nearly tripling the I3 and I6. However, the downside is it eats significantly into the run time, only maxing out at 45 minutes in this setting.
But the results are impressive: 93% in deep cleaning tests and 100% in the sand on hard floor results – two of the best scores of all robot vacuums.
Similarities between the Roomba I3, I6, and S9
Let’s quickly go through the similarities of these Roomba variants.
1. Neat rows
The first similarity between these Roomba products is each one navigates in what iRobot calls “neat rows” – a fancy term for moving in straight back and forth lines.
But the difference ends there. The Roomba I3+ has the simplest algorithm as it moves in a crisscross pattern, first in the direction of the clean base station and then across. In a way, I like the simplicity because the fewer decisions it has to make will make it more efficient.
The I3+ was the most efficient of all three, at least for the small room, finishing the two-pass run in around 22 minutes.
- Roomba I3: 22:43 mins
- Roomba I6: 28 mins
- Roomba S9: 32:33 mins
I was initially surprised, but as I analyzed it more, it made more sense. The fewer decisions it makes, the sooner it finishes since it won’t have moments of indecisiveness, something I noticed with the I6 and S9.
2. Dustbin
The Roomba I3, I4, I6, and I7 utilize the same rear-mounted dustbin with a slight capacity variation.
- Roomba I3: 500 ml
- Roomba I3+: 400 ml
- Roomba I4+: 400 ml
- Roomba I6+: 400 ml
- Roomba I7: 500ml
- Roomba I7+: 500 ml
- Roomba S9+: 500 ml
You’ll notice above, the non-plus versions having slightly higher volume. It’s because these dustbins don’t have this notch inside where the port sites for the clean base station.
These bins have narrower openings making it a bit trickier to empty.
In comparison, the
3. Clean base station
All plus versions of these robots have a clean base station, where a second vacuum in the dock empties the robot’s dustbin after every run.
iRobot is a pioneer of this technology and is one of the best at implementing it with its ramp-style design where the robot sits.
I like this over other brands that utilize a vertical port because it won’t have any alignment issues.
All three have a bagged system where all dustbin contents go into this bag. iRobot doesn’t specify the exact capacity, but I guess it’s around 2.5 liters since it has almost the same bag size as the Yeedi Vac Station.
These variants use the same bag, meaning an I6-specific bag will fit on the I3 or S9.
4. Shape
Most Roomba models have the same round shape and identical dimensions, except for the S9 with the square front and D-shape frame.
5. Rubber extractors
iRobot utilizes the same latest generation rubber extractors for all three variants. This feature is unique to Roomba products since it owns the patent.
It’s one reason why these robots do so well on carpet despite the low airflow.
These rollers provide excellent agitation and pick up debris at a high rate, but one difference is the S9 extractors are much wider than the I3 and I6, measuring over nine inches.
6. Dirt detect
Another feature unique to Roomba is “dirt detect” – it’s an acoustic sensor on the brush roll assembly that detects any increase in volume. Once it’s triggered, it tells the robot to do extra passes.
Again, you won’t see this in other brands since it’s an iRobot patent.
7. Single side brush
Along with the extractors, these robots all have a single side brush.
The I3, I4, I6, and I7 have three-pronged side brushes with longer arms, while the S9 has a smaller diameter side brush with five prongs.
One issue with the non-S9 models is their rapid-spinning nature that tends to scatter debris.
iRobot addressed this issue by toning down the velocity in the S9, improving its efficiency further.
8. Compatibility with iRobot app
These smart robot vacuums are compatible with the iRobot home app with varying levels of features.
The I3 has the simplest feature set since it doesn’t have VSLAM; thus, it cannot save maps or access containment features.
In comparison, the I6, I7, and S9 have more features, such as keep-out zones, selective room cleaning, and zoned cleaning, since it has VSLAM.
All these features (mentioned above) are usable with the scheduling feature, which adds to the convenience aspect.
Differences of the Roomba I3, I4, I6, I7, and S9
Next, let’s look at the differences between these Roomba models.
1. Power
iRobot doesn’t disclose exact power figures for their products, so I use an anemometer at the cleaning nozzle to determine power figures.
- Roomba I3: 7.27 CFM
- Roomba I6: 8.2 CFM
- Roomba S9: 25 CFM
Even if the I3 and I6 have similar power specs based on iRobot’s website, airflow tests reveal that the I6 has slightly more.
The S9 has the highest airflow results at 25 CFM, and it’s not even close. It also has more airflow than the I3 and I6 at the lowest setting at 11.33 CFM; therefore, it has enough usable power even in the lowest setting.
2. Noise levels
Loudness levels will vary between these Roomba products. Obviously, the S9 is the noisiest, with up to 74.1 decibels in the max setting, while I3 and I6 are quieter options at 64.9 and 64.5 decibels, respectively.
3. Deep cleaning performance
One difference not many reviewers mention is the variation in cleaning embedded dirt. The S9 is the best of the three options here, picking up an average of 93%, thanks to its high-end airflow.
Surprisingly, the next best result is the I3, picking up 84.7%, while the I6 plus did the worst at 82.5%.
App features of the Roomba I3, I4, I6, I7, and S9
All these products are compatible with the iRobot app, and let’s go through the features.
1. Map saving [Rooma I6, I7, and S9 only]
Only the I6, I7, and S9 variants have a map-saving feature. You can access this feature by tapping on the pin icon on the lower right portion of the robot graphic.
Users can save up to ten map levels, which is six more than Roborock and eight more than Ecovacs – two of its main competitors.
The I3 and I4 can’t save maps since it doesn’t have VSLAM or the top-mounted camera, but it can draw maps accessible through the history tab.
2. Mapping runs [Roomba I6, I7, and S9 only]
iRobot has this feature called mapping runs, where the robot goes into an exploratory mode with the vacuum motor turned off.
This feature aims to speed up the map creation process and extend run time since the motor is off.
It’s beneficial inside larger homes where the robot may not have enough juice to complete the entire task in a single run.
Since Roomba products use VSLAM and rely on a camera sensor, lights must be on to successfully complete the mapping run.
Please note that you may need to do more than one run to draw the map successfully, but to ensure the best results, keep all doors open and remove any potential roadblocks.
Yes, it’s an additional step, but camera sensors aren’t as precise as laser sensors, so you’ll have to take the good with the bad.
3. Custom room naming [Roomba I6, I7, and S9 only]
After successfully drawing the map, users can divide zones (or rooms) and name each area. There are two options: choose from a specific list or use a custom name.
4. Keep out zones [Roomba I6, I7, and S9 only]
Along with the map-saving abilities of the I6, I7, and S9, users will also enjoy the benefits of keep-out zones.
These are rectangular or square zones users can draw on the map, telling the robot to stay away from these areas.
Unfortunately, the iRobot app doesn’t have access to the invisible wall feature, where consumers can draw straight or diagonal lines as “walls” to block the robot’s path.
It’s something that other brands like Roborock, Ecovacs, Dreame have incorporated into their respective apps.
Again, the Roomba I3 and I4 variants don’t have this feature since they cannot save maps.
5. Clean zones [Roomba I6, I7, and S9 only]
Another benefit of map saving is the clean zone feature, where users can specify rectangular or square “cleaning zones.”
It’s similar to area cleaning in other brands, but with the iRobot app, users can save these areas (and name them) for easy access.
6. Adjustable power settings [Roomba S9 only]
The
7. Control number of passes [All variants]
There are three options here: automatic, one pass, and custom. Automatic lets the robot decide how many passes it makes based on the room size. One pass is self-explanatory, while custom lets users choose between a one and two-pass run.
I’d stick with the custom setting with dirt detect and let the robot dictate how many passes unless a thorough clean is needed.
8. Scheduling [All variants]
Consumers can schedule runs for all these variants, and it’s possible to schedule multiple runs per day, something absent with older Roomba variants. However, it has a minimum gap of three hours between runs; anything below it and the app will flash an error message.
With the I6, I7, and S9, consumers can use it in conjunction with map saving and clean zones features as they can choose specific rooms or zones to clean.
9. History [All variants]
This tab shows all the previous cleaning cycles and the corresponding maps. It has no actual function other than to show how much you’ve used this robot.
Airflow comparison
Since iRobot doesn’t specify power figures with their robots, not even pascal numbers, I had to use an anemometer to measure airflow.
| Power Comp | Roomba S9+ | Roomba I6+ | Roomba I3+ |
|---|---|---|---|
| Low | 11.33 CFM | 8.2 CFM | 7.27 CFM |
| Mid | 14.52 CFM | N/A | N/A |
| Max | 25 CFM | N/A | N/A |
The
This high output makes the S9 easily the best at debris pick up on surface and embedded dirt.
Cleaning comparison
As I’ve mentioned in the airflow section, the S9+ is the best cleaning Roomba option out there, thanks to the wide extractors and high airflow.
| Roomba Model | I3+ | I6+ | S9+ |
|---|---|---|---|
| Overall | 92.39% | 93.97% | 97.93% |
| Hard Floor | 95.3% | 97.57% | 99.5% |
| Sand on hard floor | 95.5% | 98.26% | 100% |
| Carpet (Surface Pickup) | 96.22% | 97.55% | 99.25% |
| Carpet (Deep Cleaning) | 84.7% | 82.5% | 93% |
There’s a noticeable gap between the S9 and the I3/I6 options.
The numbers and the eye test confirm this claim as it had the cleanest lines during the coverage test, making it the most efficient if you factor in how much dirt it gets per pass.
In comparison, the I3 and I6 are close, with the I6 having a better overall score.
Which Roomba is best on hard surfaces?
The
Here’s a before and after shot of the
It picked up pretty much everything and another proof of the high airflow: almost nothing was left on the brush assembly.
Even with the middle setting, it still picked up a decent 99.2% – a higher score than the I3 or I6.
The I6 is the next best option, with higher overall scores than the I3, which likely confirms its higher airflow numbers, something I dismissed before writing this review.
Roomba I6 sand on hard floor before and after shot.
Lastly, the Roomba I3, specifically how it did on sand on hard floors.
Edge cleaning comparison
Again, the
It’s a huge factor why this variant does so well in this area.
By the first pass, it picked up nearly everything: the edge and a good chunk in the quarter-inch crevice.
Unexpectedly, the Roomba I3 did (slightly) better than the I6 despite having less airflow. The difference isn’t much, but it’s worth noting.
Here’s a before and after shot of the I3 edge cleaning test.
And the I6 edge cleaning.
Hair wrap comparison
Next, let’s look at how well these robots resist hair tangles. For these experiments, I use five and seven-inch strands and see how much each robot picks up.
| Roomba Model | I3+ | I6+ | S9+ |
|---|---|---|---|
| 5-inch strands | 58% | 100% | 81% |
| 7-inch strands | 40% | 54% | 82% |
The Roomba I6 did the best with five-inch strands, picking up 100%, but it didn’t do so well with longer seven-inch hair, picking up only 54%.
Factoring in both lengths, the S9 did the best, picking up above 80% for both tests, while the I3 did the worst, picking up only 54% and 40% on five and seven-hair hair, respectively.
Which Roomba is best on carpet?
Without sounding like a broken record, the
I’ve tested it on various debris types, and it had the cleanest passes and left the least amount of dirt.
It was the best on both surface and embedded dirt, getting scores above 90%, consistent with the high airflow figures.
The results between the I3 and I6 are a toss-up. With the I3 doing better at deep cleaning tests and I6 on surface debris.
Run time comparison
All three variants have the same claimed run time figures at 75 minutes. But the S9 has the largest capacity battery as it utilizes a 3300 mAh lithium-ion battery, which is a necessity since it uses a bigger motor.
However, that number goes down to about 45 minutes for the S9 if you use the max setting.
The run time figures for these Roomba products aren’t all that impressive as other brands almost double it, but it shouldn’t be a sticking point as it has recharge and resume.
Noise comparison
For this test, I used a sound meter from a few feet away to measure noise, and here are the results.
| Power setting | Roomba I3+ | Roomba I7+ | Roomba S9+ |
|---|---|---|---|
| Low | 64.9 dB | 64.5 dB | 66.3 dB |
| Mid | N/A | N/A | 68.5 dB |
| Max | N/A | N/A | 74.1 dB |
The
Maintenance
Upkeep is a big part of robot vacuum ownership, and I’ll show you how in this section. I’ve written several guides on this for specific models like the 675/690, E5, I3, and S9. Check the links if you want more detailed instructions.
- Extractors: This component is, perhaps, the most abused part of any Roomba robot. Check and clean at least once a week to remove any contaminants sticking to the roller and axles.
- Side brush: Hair will wrap on it, particularly on the arms and base. Again, check at least once a week and clean as needed.
- Dustbin and filter: If you have the plus versions of these robots, there’s no need to dispose of dirt manually, as the clean base station does it for you. But check periodically (once or twice a month) for any dirt build-up inside and on the filter. Fortunately, the dustbin is washable, but the HEPA filter isn’t.
- Caster and side wheels: Dirt will stick on these components, so use a clean towel to wipe down both.
- Sensors: There is a bevy of sensors around the robot that you’ll need to wipe down, and the most critical of these are the drop sensors underneath.
- Auto empty port: The plus versions of these robots have ports underneath the dustbin where debris passes through when the base station suctions contents out. Keep this area free from any obstruction and wash it on occasion.
- Clean base station: There’s not much maintenance for the clean base station, except for replacing the bag when full. Fortunately, the iRobot app notifies users of such, and there’s no need to babysit.
Availability of Parts
There will be no shortage of replacement parts since iRobot products are popular.
The I3, I6, and I7 share many internal components like the side brush motor, battery, brush module, and such since it uses the same platform – the only difference is the I6 and I7 have the top-mounted camera.
You can buy these components in online stores like Amazon or eBay.
But, there will be better availability for the I3, I4, I6, and I7, since these variants are cheaper and have higher sales volume.
Manufacturers are more inclined to sell components for these sub-models. Because of the considerable price variance, parts like the battery are more widely available for the I-Series than the S-Series.
iRobot does sell components for all the variants listed here, including the S9, so you can use these robots for a long time and not worry about parts not being available.
Product Specifications
| Model | Roomba I3+ | Roomba I6+ | Roomba S9+ |
|---|---|---|---|
 |  |  | |
| Width | 13.34" | 13.34" | 12.25" |
| Height | 3.63" | 3.63" | 3.5" |
| Filter | HEPA | HEPA | HEPA |
| Navigation | Smart Navigation | Smart Navigation | Smart Navigation |
| Run time | 75 mins. | 75 mins. | 75 mins. |
| Recharge and Resume | Yes | Yes | Yes |
| Map Saving | No | Yes | Yes |
| Number of Maps | N/A | 10 | 10 |
| Dustbin capacity | 400 ml | 400 ml | 500 ml |
| Water tank capacity | N/A | N/A | N/A |
| Airflow | 7.27 CFM | 8.2 CFM | 25 CFM (Max) |
| Warranty | 1-year limited | 1-year limited | 1-year limited |
| Price |
Where can I buy these robots?
You can buy these iRobot products from online stores on Amazon. Check the links below for the latest pricing.
- Roomba S9+ on Amazon (w/ clean base station)
- Roomba S9 on Amazon
- Roomba I7+ on Amazon (w/ clean base station)
- Roomba I7 on Amazon
- Roomba I6+ on Amazon (w/ clean base station)
- Roomba I4+ on Amazon (w/ clean base station)
- Roomba I3+ on Amazon (w/ clean base station)
- Roomba I3 on Amazon
Disclaimer: I will earn a commission if you purchase through any of the links above, but at no extra cost to you, so it’s a win-win for us!
Which is the best option, the Roomba I3, I6, or S9?
Choosing between these Roomba items will boil down to these three questions: how much are you willing to spend, is high-end performance a must-have, and do you need the map saving feature and its benefits?
If you’re willing to pay a premium and you want the best possible performance, then the
It’s clearly the best of the three robots I’ve tested at debris pick up, both surface and embedded.
The Roomba I3 and I6 are close, with the I6 having slightly better surface cleaning results and the I3 better at embedded stuff.
However, the difference is only minimal and shouldn’t be a deciding factor.
5 Reasons to choose the Roomba S9 +
- Best in class power: The
Roomba S9 trumps most robot vacuums with its high-end airflow. - Excellent cleaning performance: It scored above 90% across the board on both surface and embedded dirt.
- Outstanding efficiency: This robot picks more debris per pass than any other robot vacuum I’ve tested so far.
- Smart navigation: Imprint smart mapping enables users to access features like keep out zones and selective area cleaning.
- Auto-empty base station: It takes out one menial task, which is emptying the robot’s dustbin.
4 Reasons to choose the Roomba I6+
- Less expensive option to the S9: If the
Roomba S9 is too costly, the I6 or I7 would be the next best option, having the same navigational features, without the high-end suction. - More efficient: It finished the coverage test four minutes faster than the S9.
- Self-emptying feature: It also has the same self-emptying feature as the S9, but for much less.
- Decent at embedded sand: The I6 picked up an average of 82.5%, the worst of the three but still one of the best scores of all robot vacuums.
4 Reasons to choose the Roomba I3+
- Cheapest option: The I3 is the least expensive option of the three models featured here.
- Most efficient: Despite not having SLAM, the I3 finished the coverage test the fastest, at around 22 minutes.
- Better than the I6 at deep cleaning: Surprisingly, the I3 did better than the I6 at deep cleaning tests with an 84.7% score despite having less airflow.
- Crisscross pattern: I’m a fan of the crisscross pattern as it provides better thoroughness, you don’t see in robots that rely on gyroscopes and optical sensors.
The Verdict: Choosing One Will Depend On Budget and Priorities
There’s no question that the
So the question is, are you willing to spend on it? If the answer is yes, it’s obviously the best option, but if not, look at the Roomba I3 or I6.
However, cleaning performance shouldn’t be a deciding factor between these variants since it’s too close.
It’s whether you need the map saving feature the I6/I7 brings and the convenience features it brings to the table.
If it’s a need, go with the I6 or I7. Otherwise, save some cash and opt for the more efficient Roomba I3.
