Robot vacuums and door thresholds: how high can they climb?

Typical climb heights by robot type

Most robots climb by driving their front edge onto the obstacle and letting the sprung drive wheels push the body up and over. That approach is limited by wheel size and ground clearance, so stated limits for mainstream robots tend to sit around 2 cm. A newer group of premium robots adds a lifting chassis or retractable legs that raise the body to step over higher obstacles.

The figures below are the makers' stated limits from the listings. Real-world results depend on the shape of the threshold: a sloped edge is easier than a square step of the same height.

Thresholds in UK homes

Most UK homes have a few different kinds of threshold. Metal door bars and carpet grippers where carpet meets hard floor are usually low and gently sloped. Laminate and wood transition strips sit a little proud of the floor. Timber door sills, common in older houses and on doors into extensions or conservatories, can be much taller and have a square front edge. Shower trays and step-down rooms are another matter, and robots should be kept away from them.

Thick rugs and deep-pile carpet behave like thresholds too: the robot has to climb the edge before it can clean the pile. For carpet-heavy homes, our carpet guide covers robots that handle edges and pile well.

How to measure your thresholds

Measure in millimetres, and measure from the side the robot will approach from, because a strip that is 10 mm proud on the carpet side may be 18 mm proud on the hard-floor side.

1. 1

   Find the tallest threshold on the robot's route, usually an internal door sill or the edge of a thick rug.

2. 2

   Lay a ruler flat on the lower floor, against the threshold.

3. 3

   Read the height of the top edge in mm from the lower side.

4. 4

   Note whether the front edge is sloped or square; square edges are harder.

5. 5

   Compare with the robot's stated climb. Within 2 mm of the limit is borderline.

Ramps, settings and other fixes

If one threshold is just too tall, a threshold ramp is the simplest fix. Small rubber or plastic ramps sit against the sill and give the robot a slope to drive up. Choose one rated for the height you measured, and make sure it does not create a trip hazard in a busy doorway.

Some apps also help. On many models you can enable a threshold or obstacle-crossing mode, and some Roborock listings mention automatic threshold passage. Exact options vary by model and firmware, so check the maker's app or manual. If a doorway is never going to work, set a virtual wall so the robot does not keep trying, and carry it into that room when needed.

Our clearance check tool compares your highest threshold in mm with a robot's maximum climb and tells you whether it climbs, is borderline, or will not make it. It checks furniture gaps at the same time.

• Fit a ramp to a single tall sill.
• Turn on a threshold-crossing mode if your app has one.
• Use a virtual wall where a sill cannot be crossed.
• Choose a robot with a lifting chassis for homes with many tall sills.

Does a higher climb come with trade-offs?

Lifting chassis and legs add moving parts, and robots with them tend to sit at the top of each maker's range. They also matter less if your home is mostly one floor finish with flat door bars. A robot with a standard climb of around 20 mm is enough for many flats and modern houses.

Height is the other half of the picture. A robot that climbs high but stands tall may still fail to get under your sofa. Our low-profile robot vacuums guide lists both figures for each pick, and our explainer on robot vacuum height and clearance shows how to measure under furniture.

See low-profile robot vacuums →

Frequently asked questions

Which robot vacuum can climb the highest thresholds? Among current listings, robots with lifting legs or chassis state the highest figures, such as the Dreame X50 Ultra and L50 Ultra at 6 cm and the Roborock Saros 10R at 4 cm according to their listings.

Do robot vacuum threshold ramps work? Yes, for a single tall sill a ramp is a simple and effective fix. Pick one rated for your sill height and check it sits firmly without sliding.

Where are the Roborock threshold settings? On many Roborock models, obstacle and threshold options sit in the robot's settings in the app, but names and availability differ by model and firmware. Check the Roborock app or the manual for your model.

Why does my robot get stuck on a threshold it should climb? Square edges, a dirty or worn wheel, or a mop pad dragging on the sill can all stop it. Clean the wheels, check the mop is lifted if your robot can lift it, and approach the sill head on if it keeps catching.