Mowers
A slope changes which specifications matter. Weight stops being a durability question and becomes the thing you are pushing uphill; drive stops being a convenience and becomes the difference between finishing and not; and for a robot, a single published percentage decides whether the machine works at all. Four of these six publish a slope limit. Two publish a drive and a weight instead, and that is the honest alternative.
On a flat lawn, weight is a durability and storage question, drive is a convenience, and the interesting figures are the deck width and the cutting height.
On a slope the list inverts.
Weight becomes the load you are moving uphill, and the force that wants to take a machine downhill without you.
Drive becomes the difference between the far end being cut and not.
And for a robot, one published percentage decides whether the purchase works at all.
50 per cent on one. 45 per cent on three.
Fifty per cent is a gradient of one in two — about 26 degrees. Forty-five is about 24.
That is a bank you can walk up without using your hands and would not carry a full watering can down. It is steeper than most garden slopes and it is not steeper than all of them.
Measure the steepest section, not the average. The commonest shape of a sloping garden is a lawn that falls gently for most of its length and then drops the last two metres onto a patio or a wall — and that last two metres is the part a robot fails on, while the average gradient looks comfortable.
A robot on a slope past its rating does not simply cut less well.
The wheels spin. Traction fails, the mower stops climbing, and it sits there.
It beaches sideways. A mower traversing a slope steeper than it is designed for slides down the fall line and ends up across it, where it has less grip again.
It wears a patch. A robot that keeps trying the same approach grinds the same piece of turf until it is bare, at the bottom of the bank, which is also where the water collects.
And it stops navigating. Every robot on this page positions itself continuously, and wheel slip corrupts that. A machine that thinks it has travelled three metres and has travelled one is a machine that maps the garden wrong.
One of these also publishes the related figure: 3 cm of obstacle clearance. On a slope that matters twice over, because a lawn edge crossed uphill is a higher step than the same edge crossed on the flat.
It is worth stating because it is the strongest argument on this page.
You do not walk the slope. Not once a week for seven months.
A sloping lawn is the single most unpleasant mowing job in a domestic garden, and it is where most accidents with mowers happen: a heavy machine, wet grass, a downhill gradient and arms that have been working for twenty minutes.
A machine that goes up and down it on its own removes the job rather than making it easier, and all four robots here publish a slope figure to be held to.
If a robot is not the answer — too much lawn, too little budget, too many obstacles — then the requirement changes to drive.
Both petrol picks here are rear-wheel drive, and one publishes the two figures that go with it: 35.1 kg, and a named transmission maker.
Thirty-five kilograms is why drive matters. On the flat it is invisible. Up a 20 per cent bank it is the whole task, and the arms doing it are also the arms steering a machine with a spinning blade under it.
A named gearbox is why it keeps mattering. A self-propelled drive is the part of a petrol mower that fails, and a transmission from a named maker is a repairable one rather than an anonymous assembly.
The other publishes its speed — 3.7 km/h — which is the figure that tells you whether the drive walks at your pace or drags you.
Guaranteed sound power.
Not one of the six publishes a decibel figure, and neither does any petrol mower this site has surveyed.
It is worth naming here because a sloping garden is usually a terraced one, which means the neighbours are above or below you at close range — and two robots on this site’s shelf publish figures under 55 dB and 58 dB while the petrol machines publish nothing at all.
Mow across a slope, never up and down.
Three reasons and all of them matter more than the tidiness of the stripes:
The machine cannot run away. Pointed across the fall line, gravity is not pulling it in the direction it travels.
It cannot come back at you. A pushed mower that slips while pointed uphill comes downhill, and you are what is downhill of it.
Your footing is better. Walking across a slope is stable; walking backwards down one while pulling 35 kilograms is not.
And the condition that overrides all of it: not on wet grass. A slope that is manageable dry is a different surface an hour after rain, and the machine is the least of what slides.
Cut it higher than the rest of the lawn.
A slope dries faster than flat ground — water runs off it rather than in — so grass on a bank is under more drought stress than grass ten metres away. Longer grass has more leaf, deeper roots and better drought tolerance, and a bank cut at 50 mm survives an August that a bank cut at 25 does not.
Which is also the setting that reduces how often it has to be cut, on the part of the lawn nobody wants to visit.
3D + HDR camera, mapping to 3 000 m², 50 % slope, under 55 dB
Long-range 3D scanning with an HDR camera, an extending cutting head for edges, a 26.5° slope and a camera that patrols the garden.
Best for: A large garden with slopes and a lot of edge, for an owner comfortable with an app and a camera
RTK + vision, 600 m², 30–80 mm in 10 mm steps, 45 % slope
Satellite positioning with a visual fallback, 1 cm height steps from 3 to 8 cm, 45 per cent slopes and 0.7 m passages.
Best for: An open garden of moderate size with slopes and narrow links between areas
190 mm cut, 3 cameras, 45 % slope, 55 cm passages, 4.5 Ah
Three cameras working together, a 19 cm cut on five swinging razors, 55 cm passages, and a mode that mows without mapping first.
Best for: A garden of several small linked areas with narrow gaps between them
3D LiDAR + vision, edge within 5 cm, 45 % slope, 30–100 mm
Laser scanning plus vision, a sliding blade disc that cuts within 5 cm of a wall, 45 per cent slopes and 60 cm passages.
Best for: A large, complicated garden with slopes, narrow links and a lot of hard edge
55 cm, 224 cm³, 5.2 kW, rear drive, 60 L, 30–80 mm, 35.1 kg
The widest deck and the only published weight in this family: 224 cm³, 55 cm, 35.1 kg, with assembled dimensions and both wheel sizes given.
Best for: A large open lawn where width and engine matter more than the machine being easy to put away
51 cm steel deck, 166 cm³, self-propelled 3.7 km/h, 60 L
A 51 cm steel deck on a 166 cm³ engine, self-propelled at a stated 3.7 km/h, with a 60-litre hybrid box — and a price in five markets.
Best for: A medium to large lawn, and the one machine here whose price can be checked against another country
About 24 degrees — a bank you can walk up without using your hands but would not carry a full watering can down. Fifty per cent is 26 degrees. Measure the steepest section, not the average: a lawn that runs gently down and then drops two metres to a patio is a 45 per cent lawn at the bottom, and that is the part a robot will fail on.
Because it is a hard limit rather than a soft one. Past the stated figure the wheels spin, the mower beaches sideways, and a strip of lawn never gets cut — and a robot that keeps trying wears a bare patch at the bottom of the bank. Four of these six publish a percentage; two robots on this site’s shelf publish none at all.
Far more. A petrol mower weighs around 35 kilograms, and on the flat that is pushed without thinking. Up a bank it is the entire job, and it is also what makes the job unsafe — a heavy machine on a wet slope with tired arms is how people are hurt. Both petrol picks here drive their own rear wheels.
Across it, not up and down — for a pushed mower, always. Mowing across keeps the machine’s weight beside you rather than above or below you, and it means the machine cannot run away downhill or come back at you. A robot decides for itself, which is one more argument for letting it.
For : A large garden with slopes and a lot of edge, for an owner comfortable with an app and a camera
Main strength : The longest sensing range stated on this shelf, at 70 metres
Main limitation : The decibel figure does not say whether it is sound power or sound pressure
For : An open garden of moderate size with slopes and narrow links between areas
Main strength : A visual fallback stated for weak-signal areas, which is where RTK alone fails
Main limitation : A reference station is part of an RTK installation and its siting is a real constraint
For : A garden of several small linked areas with narrow gaps between them
Main strength : A published cutting width and a published cutting system — five free-swinging razors
Main limitation : No charge time and no weight
For : A large, complicated garden with slopes, narrow links and a lot of hard edge
Main strength : The widest cutting-height range on the shelf, 3 to 10 cm
Main limitation : The stated area appears only in the model name, not as a published figure
For : A large open lawn where width and engine matter more than the machine being easy to put away
Main strength : The only published weight and the only published assembled dimensions in the family
Main limitation : 35.1 kg is a lot of machine to manoeuvre, store and lift into a car
For : A medium to large lawn, and the one machine here whose price can be checked against another country
Main strength : Listed in five markets, so the price comparison this site makes is available on it
Main limitation : No cutting-height range at all, which on a mower is the setting that matters most
Head-to-heads already published between two models from this guide or this aisle.
The models here come from the catalogue of this site. Specifications are those published by the manufacturer and on the Amazon product page; prices are what Keepa reported on the date below, and both move. The ranking uses declared specifications, the balance of stated strengths and limitations, and price. No product on this site has been physically tested, and nothing here claims otherwise.
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A mower gets bought when the grass is already too long, which is the worst possible moment to weigh up a price: demand on this shelf climbs from March and drops away after July, so a price struck through in May tells you nothing whatever about what the same reference cost in October. UniverTrack keeps a week-by-week record for each retailer, so a cut price can be set against one somebody really paid rather than one composed for the banner — and it says when ordering is genuinely the moment.
