By Samuel Williams

The Roomba vacuums have entirely improved the task of vacuuming our homes. While your Roomba is doing its job, you can do your other things. But, whether you’ve had your Roomba for a short or a long time, you may have seen that it stops cleaning on its own. While your Roomba does this, have you ever wondered: how does Roomba know when to stop cleaning? Is there some magic involved?

You surely want to find out, right? Friends, the wait is over because we are about to tell you the truth about how your vacuum cleaner determines when to stop.

Although you can manually stop it, your Roomba includes a built-in mechanism that notifies you when to stop cleaning, temporarily or permanently. This article will explain how your Roomba moves through and cleans your house before stopping and heading back to its port. So, let’s begin.

How Does Roomba Know When To Stop Cleaning

Let’s get right to the facts, ultimately the basis for your Roomba’s ability to choose when to stop cleaning. The following are the factors that may lead your Roomba to stop vacuuming:

  1. Battery is low
  2. Dustbin is full
  3. When it finishes a cleaning job

1. Battery Is Low

This may be the cause for your Roomba’s realization that it is finally time to stop cleaning and rest for a while. When the battery in your Roomba becomes low while it is cleaning, you should expect it to quit.

Theoretically, it won’t operate when the battery is low, so if it reaches the point when it is running low, it will stop cleaning, recharge at the charging dock, and resume cleaning.

2. Dustbin Is Full

When your robot’s dustbin is full,  it is also alerted that it is time to stop. When this occurs, the robot’s bin full indicator will blink, telling you that the hopper needs to be emptied.

If it has Wi-Fi capability, you will get a notification on your smartphone when the Roomba’s bin is full. When you empty the trash and select the Clean button, Roomba will start operating again.

3. When It Finishes A Cleaning Job

when it finishes its task

This is the other, most significant factor that answers: how does a Roomba know when it’s done? It ensures your Roomba that its task is now finished and it can rest now. How did that occur, too? Okay, this is the part when things start to get interesting. For your better understanding, we have separated this section into two parts, which are:

  1. The sensor and mapping algorithm
  2. Virtual wall and lighthouse technology

1. The Sensor And Mapping Algorithm

The essential feature of your Roomba is its sensor and mapping technology, which enables it to recognize when its cleaning is complete and stop.

The Roomba vacuum cleaner has built-in sensors that allow it to perform most of its functions. The machine can map the house using the sensors to choose the best route for vacuuming. These sensors allow the vacuum cleaner to begin cleaning and notify it when to stop.

The mapping algorithm knows the swept area size, the unit’s speed, the duration between collisions, and the turns influenced by the collision. In other words, the sensors in your Roomba efficiently map the space, recognize when it has thoroughly cleaned the floor, and know when and how to reach missed locations.

The types of sensors listed below will help you to better understand how your Roomba will use them:

Front And Bumper Sensors

The robot’s first sensor, which produces infrared beams to detect walls and objects, is at its top. Moreover, a touch-sensitive sensor is located directly beneath the robot. Both not only assist the Roomba in avoiding obstructions but also in detecting the distance between a room’s center and its walls, allowing it to calculate the size of the space and the recommended cleaning time.

Cliff Sensors

Cliff sensors are located beneath the vacuum, and when they detect steep terrain, such as stairs, they shine their downward-facing infrared beams to signal the vacuum to stop and turn around. If the robot thinks it might get tangled in a rug or between pieces of furniture, it will also stop and change course.

Dirt Sensors
roomba's dirt sensor

The Roomba uses dirt sensors to identify regions of a room that are incredibly unclean so that it can devote more time to cleaning that area.

To calculate how long it should clean before stopping and returning to its home base, Roomba takes a variety of things into account, including the size of a room, barriers, and the amount of dirt. And now that you know how your Roomba benefits from these effective sensors. The mapping technology in your Roomba gets even more exciting in the section below. Let’s look at it.

Here, is a table showing the sensor types and their functions.

Sensor TypeFunction
Front and BumperDetect walls, objects, and room dimensions
Calculate cleaning time
Cliff SensorsDetect steep terrain like stairs
Prevent falls by signaling vacuum to stop
Dirt SensorsIdentify heavily soiled areas
Allocate more cleaning time for such areas
Table: Roomba Sensors And Functions

Vision Simultaneous Localization And Mapping (VSLAM)

Some Roomba models come with a unique technology called Vision Simultaneous Localization and Mapping in addition to the sensors (VSLAM). This gives these more recent Roombas an advantage over other robot vacuums regarding cleaning effectiveness and adding a layer of intelligence.

While current and some of the best Roomba models, including the i7 and the 980, clean more strategically, older models clean randomly. These models’ VSLAM technology employs beacons and cameras mounted on the camera to take pictures of every room and gradually create a map of your house.

The robot can determine where it has and has not been cleaned, thanks to mapping technology. Cleaning becomes quicker and more effective as a result. Thanks to room mapping, the robot can stop vacuuming when the battery is low and resume after recharging. And also after cleaning the designated area, the robot automatically stops and returns to its charging dock.

2. Virtual Wall And Lighthouses

virtual wall and lighthouses

Following the sensor and mapping technologies, your Roomba’s virtual wall and lighthouse feature is an excellent feature that is present in many recent models. 

The robot can recognize the boundary between different rooms in the house thanks to the infrared light that the lighthouses emit. The robot may clean a room completely in this manner before moving on to the next.

The activated virtual wall feature in your Roomba prevents it from cleaning some blocked-off areas. For instance, If you want to prevent the Roomba from entering your bedroom while sleeping, you can build a virtual wall.

The Roomba i7+ is an intelligent vacuum worth looking into if you want something even more advanced in terms of room mapping. This most recent Roomba maps out your house and remembers each room’s location, dimensions, and shapes.

This implies that you can set your robot to clean particular rooms on particular days of the week. The robot will only finish its cleaning session after it has cleaned those specific rooms, except when pausing to refuel.

How To Use A Virtual Wall Lighthouse | Roomba® 800 series

How Do I Know When Roomba Is Finished?

how do i know when roomba is finished

In contrast to a typical vacuum, Roomba doesn’t require your presence to operate. The Roomba is a little robotic vacuum cleaner made by iRobot Corp that can detect the size of a room using infrared technology.

Once it has finished mapping, it sweeps the entire floor to remove dirt and debris. You can tell when your Roomba has finished cleaning once it has finished its cleaning cycle.

The steps involved in your Roomba’s cleaning cycles are listed below. Let’s see how it works.

Step 1

Insert the Roomba’s charger into its home base and plug it into an outlet. When the Roomba battery is running low, a flashing amber light will start to charge the battery.

Step 2

When the charging battery switches from amber to green, press the “Clean” button. This shows that the battery is completely charged. You must push the “Clean” button for the Roomba to start a cleaning cycle.

Step 3

Let the Roomba continue to clean the floor as it moves around the room. With the use of an inbuilt “dirt sensor,” it will find dust and filth.

Step 4

Watch as the Roomba automatically returns to its home base charging station. The cleaning cycle is over, and your floor will be vacuumed once the Roomba has returned to its home base. According to the size and shape of the space you are cleaning, this process typically takes 25 minutes for an average-sized room, but it may take longer or shorter.

How Long Does The Roomba Clean For?

The subject of how long your Roomba clean has become relevant in light of our discussion of how precisely it knows when to complete a task. Typically, a fully charged Roomba takes between 60 and 120 minutes to clean a floor area of roughly 2,000 square feet

The size of the room and the Roomba’s runtime is different for each model. Your Roomba’s runtime and the size of the room determine the precise amount of time it takes to clean. 

Yet again, additional elements affect how long Roomba will clean. Among these elements are;

The Roomba brand: The shortest Roomba runtime is 60 minutes for the Roomba 890, while the longest runtime is 120 minutes for the Roomba s9 or s9+. As a result, the Roomba 890 requires a recharge after an hour of cleaning, and the Roomba s9 requires a recharge after two hours of cleaning.

Floor-type (hardwood or carpet): As carpet floors are thicker, they use more battery power than hardwood floors.

Furniture and square feet: If your house is large and overstuffed with furniture, the Roomba will take considerably longer to clean it.

Roomba model: A 300-square-foot area may be thoroughly cleaned by an older Roomba model from the 600–800 series during the allotted 1 hour of battery life. Then you must return it to its charging port. And once it has fully charged, you can still send it to continue cleaning.

Modern Roomba models from the 900 series clean systematically and linearly, allowing them to keep track of their travels. Its “Charge and Resume” feature forces it to return to its charging point when its battery level drops.

The Roomba 900 series model can accomplish the task in around 2 hours 30 minutes, including the time it takes to charge, or about 90 minutes for a cleanable area of about 636 square feet. If you put the Roomba in a compact space, it will choose to make more cleaning passes without worrying about running out of charge.


  • Roomba’s ability to determine task completion enhances cleaning efficiency.
  • Roomba takes 60-120 minutes to clean around 2000 sq. ft. area, catering to various needs.


  • Cleaning time varies due to room size, furniture, and battery life, potentially leading to inconsistencies.
  • Longer cleaning times might be constrained by the Roomba’s battery life, necessitating recharge breaks.

Why My Roomba Never Finishes Job?

why my roomba never finishes job

Does it take too long for your Roomba to finish cleaning? As was said in the section above, the typical time for a Roomba to finish cleaning is about an hour. Roomba vacuum cleaners aren’t supposed to take forever when cleaning your house. Even though a few variables affect how long a Roomba will clean, an abnormally long cleaning time isn’t good. That implies that there may be a problem with your Roomba.

Try some of these solutions if your Roomba is taking an eternity to clean or never completes its task; 

  • Make sure to thoroughly clean your Roomba. Clean the rollers, bin, brushes, filters, and sensors. Your Roomba may be slowing down due to dirt buildup.
  • Consider using your Roomba to clean a single room at a time. Keep track of how long each room takes and see if there are any surprises. If so, look around the space for anything obstructing your Roomba’s path.
  • Verify the map’s accuracy today. The map on Roomba vacuum cleaners may occasionally be updated, which may cause it to degrade over time. Replace the damaged map with a good one from your cleaning history, or redo your house’s map if necessary.
  • Make sure the battery is in good condition. Your Roomba returns to the charging station after only 10 to 20 minutes of vacuuming due to a bad battery. Due to the constant need for recharging, your Roomba takes an eternity to complete a task. Your battery needs to be replaced if this is the situation. To keep your warranty from expiring, purchase an original iRobot Roomba battery.


So wondering how does Roomba know when to stop is no longer rocket science. Making Roomba models operate smoothly and keep your home clean takes a lot of effort. The array of built-in sensors significantly contributes to the robot’s ability to complete the task and stop when necessary. Also, if your dustbin is full and your Roomba battery is low, the robot will most likely stop working.


Does the Roomba stop when it’s full?

The Roomba displays a specific behavior when the dustbin is full. In this case, there are two options: either it will keep cleaning until the entire area has been cleaned, even if the trash can is full, or it will first empty the trash bin and then restart the new cleaning task. 

How often does a Roomba need to be emptied?

Most robot vacuum manufacturers advise emptying the dustbins of their machines after each cleaning session. With their Roomba and Botvac models, iRobot and Neato advise doing this.

How does Roomba know where to go

While humans see with their eyes, a Roomba navigates a room using infrared and photocell sensors. Cliff sensors alert the vacuum when it is close to a “cliff,” such as stairs or a balcony. These sensors all have various functions. The vacuum will move away from the ledge if it detects this.

Does Roomba clean during the mapping run?

The robot can map while cleaning as long as Smart Maps is turned on.   In a special mapping run mode, your robot will move around your house without cleaning, allowing it to run for longer on a single battery charge.

How long does a Roomba take to clean a room?

A Roomba takes 45 minutes to 2 hours to clean a room, varying based on room size and dirt level.

What is Roomba doing when it pauses?

When a Roomba pauses, it may be adjusting navigation, recharging, or encountering obstacles that require navigation adjustments.

External Resources

Leave a Comment