Robot vacuum dock bags: sizes, fit and how often to change them

How a self-emptying dock and its bag work

When the robot returns to a self-emptying dock, a strong fan in the base sucks the dust out of the robot's bin through a port underneath and blows it into a bag or bin in the dock. On all-in-one docks, the same base also holds clean and dirty water tanks for mopping, but the dust side works the same way.

The bag is sealed at the inlet, so when you lift it out the dust stays inside. That is the main appeal for many households: you deal with dust every few weeks rather than every day. The bag also acts as an extra filter, which is why its fit and material matter.

How long a bag lasts depends on the bag size, the size of your home, pets, carpets and how often the robot runs. Makers quote figures such as days of hands-free cleaning, but these are best treated as rough guides rather than promises.

Dock bag sizes by model

These capacities come from the makers' current UK listings. Where a listing gives a different figure on another version of the same product, both are shown. Check your own dock's manual before buying bags, because similar names can hide different bases.

Compare self-emptying robots →

How often to change the bag

The simplest rule is to change the bag when the robot's app or the dock tells you it is full, or when the dust reaches the fill line if the lid has a window. Most current apps send a reminder, and many docks stop emptying when the bag is full or missing.

A bigger bag does not always mean fewer changes. A 5 litre bag in a large house with a long-haired dog may fill faster than a 2.5 litre bag in a small flat. Pet hair is bulky and fills a bag faster than fine dust.

Do not wait until a bag is crammed. An overfull bag restricts airflow, so the dock may leave dust in the robot's bin. If the robot starts reporting a full bin straight after emptying, check the bag first, then the evacuation port on the robot and the duct in the dock for a blockage.

1. 1

   Open the dock lid and lift the bag out by its handle or cardboard collar; on most docks this closes the inlet.

2. 2

   Put the old bag straight into the bin outdoors to keep dust contained.

3. 3

   Wipe dust from the bag holder with a dry cloth.

4. 4

   Slide in a new bag until the collar clicks or seats fully, then close the lid.

5. 5

   Reset the bag counter in the app if your model has one.

Genuine versus compatible bags

Genuine bags are made for the dock's collar shape and seal, and the maker has matched their material to the base's airflow. Compatible third-party bags are widely sold and often cheaper per bag, and many work fine. The risks are a poor seal, which can let dust escape into the dock, and a thinner material that tears or lets fine dust through.

If you try compatible bags, buy from a seller that names your exact robot and dock model, check that the collar matches the original and that the bag sits flat. Keep an eye on the dock compartment for dust after the first few empties. If dust leaks round the edge, go back to genuine bags.

Some multi-pack accessory kits combine bags with brushes, filters and mop pads. These can be handy, but check every item is listed for your model, because Roborock, Dreame, Eufy and others use different parts across their ranges.

Bagless bases and robots without a dock

If you would rather not buy bags at all, some robots use a bagless base. Shark's Matrix and Navigator self-empty models use a bagless dock with a bin you empty. Ecovacs offers bagless emptying on the DEEBOT N20e Plus and its X12 OmniCyclone. The Lefant M2 Pro and Proscenic Q20Plus also use bagless collection bases.

Bagless bases save on consumables, but you empty a bin by hand, which can release some dust. Doing it outdoors or straight into a bin liner helps. The filter in a bagless base also needs regular cleaning.

A different approach is the iRobot Roomba 205 DustCompactor, which compacts debris inside the robot itself and has no emptying dock. That keeps the footprint small, which may suit a flat; see our guide to the best robot vacuum for small flats.

• Bagged dock: most hygienic to empty, ongoing bag purchases.
• Bagless dock: no bags to buy, you empty a bin and clean a filter.
• No dock (compacting robot): smallest footprint, you empty the robot directly.

Frequently asked questions

Do Roborock, Dreame and Eufy bags fit each other's docks? No, assume they do not. Each maker uses its own collar and seal design, and it can even vary between docks from the same maker. Buy bags listed for your exact model.

Can I empty and reuse a dock bag? Disposable bags are designed for single use. Reusing them weakens the material and the seal, and dust can escape into the dock. Fit a new bag instead.

Is there a robot vacuum and mop without a dust bag? Yes. Some all-in-one and self-emptying robots use a bagless base, such as the Ecovacs DEEBOT X12 OmniCyclone and N20e Plus, and Shark's bagless docks. You empty a bin instead of changing a bag.

Why does my dock not empty the robot properly? A full bag, a bag that is not seated, or a blockage in the robot's evacuation port or the dock duct are the common causes. Check those first, then see our guide to a robot vacuum that won't dock if it is not connecting at all.