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Roomba i3 vs s9 (2021): Which Robovac Should You Choose?

iRobot has added several robot vacuums to its lineup since they released the first-ever Roomba floor vacuuming robot in 2002. From budget-friendly models to high-end models. 

In this article, we’re taking the budget-friendly Roomba i3 and comparing it to the high-end Roomba S9 to see whether or not the additional features and cleaning power on the S9 are worth the extra $500 or so you spend for them.

Roomba i3 and S9 Comparison Chart

ModelRoomba i3Roomba s9
Suction Power10x suction power compared to Roomba 600 series40x suction power compared to Roomba 600 series
Smart MappingNoYes
Smart NavigationYesYes
Cleaning SystemPremium 3-stage cleaning systemPremium 3-stage cleaning system
Tangle Resistant BrushesYesYes
Clean Base Automatic Dirt DisposalNoOptional
Create Keep Out ZonesNoYes
High Efficiency FiltersYesYes
Imprint LinkYes, with Braava jet m6 robot mopYes, with Braava jet m6 robot mop
Voice Assistant Alexa and Google AssistantAlexa and Google Assistant
Dimensions13.26″ x 3.63″12.25″ x 3.5″
Weight7.44 lbs8.15 lbs


The Roomba i3 comes in the traditional circle shape while the S9 comes in a unique D-shape for better corner cleaning

Roomba i3 (left) and Roomba S9 (right)

At first glance, the most noticeable distinction between the Roomba i3 and the S9, aside from color, is their shape. The i3 sports the original circle design found in most of iRobot’s Roomba robovacs while the S9 comes in a D-shaped design for better corner cleaning. The Roomba i3 is the bigger one compared to the S9 but the S9 has a little more weight. The i3 measures roughly 13.5 inches in length and width, 3.5 inches high, and weighs a little over 7 pounds. The S9 measures an inch less than the i3 in length and weighs half a pound heavier. 

Both robovacs come with black plastic bumpers, minimalistic buttons on top, and advanced cleaning technology underneath. The Roomba S9 also has a little camera on top to help with navigation. The Roomba i3 comes in black and grey. It has a cloth-like texture on top that gives it a modern simplistic look. The S9, on the other hand, comes with a brushed copper disc up top which makes the robovac look very premium.


The Roomba S9 takes an easy win when it comes to cleaning with wider cleaning brushes, 30x more suction power, and PerfectEdge technology for better edge cleaning

Cleaning technology underneath the Roomba i3 (left) and Roomba S9 (right)

Both the Roomba i3 and S9 use iRobot’s 3-stage cleaning system which lifts, loosens, and eliminates debris and even pet hair from deep within your carpet floors. Underneath these robovacs, you’ll find two multi-surface rubber brushes for deeper cleaning and edge brushes positioned at an angle to reach tight edges and corners. The i3 and S9 come with Dirt-Detect sensors that detect concentrated areas of dirt and prompts your robovac to work harder on those areas. They also have auto-adjust cleaning heads that will automatically adjust the height of the brushes to clean carpets and hardwood floors more effectively. 

When it comes to cleaning, the Roomba S9 has the advantage. It comes with 30% wider rubber brushes for more efficient cleaning, five 30mm corner brushes (versus the i3’s three brushes) that go in a circular motion, and 30x more suction power compared to the i3. The Roomba S9 also has PerfectEdge technology which is the square shape of the front half of the robovac for reaching dirt in corners more effectively. With the higher price tag of the Roomba S9, you get more cleaning power.

One really convenient feature the Roomba i3 and S9 come with is the recharge and resume feature. When your robovac is running out of juice, it immediately heads over to its charging dock to recharge. Once fully charged, it heads right back to work on the exact spot it left off. This means you never even have to think about recharging your robovac.


The Roomba S9 has the edge in navigation with its advanced vSLAM navigation technology

Roomba i3 (left) cleans in neat rows, Roomba S9 (right) has customizable keep-out zones

The Roomba i3 and S9 both come with smart navigation technology. They are equipped with advanced sensors to find their way around your house and clean your floors in neat rows. With their mapping systems, these robovacs will never miss an unclean spot on your floor. 

The Roomba i3 is equipped with reactor sensors that help it navigate around obstacles and prevent itself from falling off stairs or getting stuck underneath furniture. The reactor sensors are accurate and work well but they don’t work quite as accurately as the Roomba S9’s visual navigation. Remember that little camera sitting on top of the Roomba S9? That’s part of the Roomba S9’s vSLAM navigation technology that captures over 200k data points per second to optimize coverage and navigation. 

When it comes to mapping, the Roomba i3 does a good job of mapping a room and going over every corner making sure it’s nice and clean. On the Roomba S9, you get a more advanced mapping system. With Imprint Smart Mapping, your S9 can map different rooms in your house and store that information so you can easily decide where it cleans and when. You are even able to map specific objects like a kitchen table or the couch in the living room. This allows you to quickly send your S9 to any the mess, right when it happens.  

Because of the Roomba S9’s advanced sensors, you are also able to customize Keep Out Zones. These are square zones that you create on the iRobot Home app to prevent your S9 from cleaning in those areas. These zones might be where there are fragile pieces of furniture or perhaps pet bowls that you want your S9 to stay away from.

Other Features

With the iRobot Home app, you can create cleaning schedules, setup keep-out zones, and get cleaning suggestions based on your cleaning habits

Both the Roomba i3 and the S9 can be integrated into your smart home system and take commands from Google Assist or Alexa. With the iRobot Home app, you can set up Keep Out Zones for your Roomba S9 and create cleaning schedules for both the S9 and i3. The app will also suggest cleaning schedules based on your cleaning habits and when pollen count is high or during pet shedding season. 

With the Roomba S9, you can also purchase a separate automatic disposal base, which doubles as a charging base. Whenever your S9 is full, it automatically deposits what’s inside its vacuum bag into the base so your S9 can continue cleaning. This means you can completely forget about vacuuming for months and still have clean floors and carpets every day.


The Roomba S9 is perfect if you’re looking for superior cleaning power and navigation while the i3 will be an excellent choice if you’re a first-timer or looking for a budget-friendly robot vacuum

The Roomba i3 and Roomba S9 are two great robot vacuums that do an excellent job of keeping your home clean. The more expensive Roomba S9 has better cleaning technology and a handful of additional features that make it the more convenient robot vacuum compared to the i3. If you have money to spare, the Roomba S9 is an easy winner.

If, however, you don’t want to spend an additional $500 or so for features like advanced mapping, stronger suction, and more effective cleaning brushes, the Roomba i3 will be an excellent choice. It is considered the entry-level robot vacuum perfect for those who are getting a robot vacuum for the first time.


📌 How much battery life does the Roomba i3 and S9 have?

The Roomba S9 can clean for 2 hours before running out of juice while the i3 can run for 75 minutes.

📌 Can I purchase an automatic dirt disposal base for the Roomba i3?

Unfortunately, the Roomba i3 does not work with automatic dirt disposal bases. You will have to purchase the Roomba i3+.

📌 Is there a difference between the multi-surface brushes of the Roomba i3 and the Roomba s9?

The Roomba s9’s dual-surface brushes are 30% wider compared to those on the Roomba i3.

📌 Can the Roomba i3 automatically recharge itself and resume cleaning?

Yes, the Roomba i3 will make its way to the charging base when battery levels are low for a recharge before resuming its cleaning job right where it left off.

Last update on 2022-08-14 / Affiliate links / Images from Amazon Product Advertising API

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Manolo Martinez

Senior Editor at Compare Before Buying. Writer and researcher passionate about music, film, and DIY projects.