How much suction do you need?
Pa is the most misunderstood number in the category. It measures static pressure, not cleaning ability — and beyond a point it changes nothing except the price. This works out the band that matches your floors, then tells you where the extra money should go instead.
Once you know your band, compare current models that actually meet it rather than the ones with the loudest marketing. See robot vacuums → Advertising — we may earn a commission.
Does it pay for itself?
A robot vacuum does not replace cleaning — it replaces the routine passes between deep cleans. If you pay for a cleaner, or value your own time, that has a number attached. Here it is.
Runtime vs floor area
The advertised runtime is measured on the quietest setting, on bare floor, in a straight line. Real homes have furniture, carpet and doorways. This estimates whether one charge will actually finish your floor.
Will it actually fit?
The most common regret is a vacuum that cannot get under the sofa, or a dock that does not fit where you planned to put it. Measure once, here, before ordering.
Robot mower sizing
Mowers are sized by lawn area and slope, and both matter more than any feature on the box. Undersize it and it runs constantly; oversize it and you have paid for capacity you never use.
Boundary-wire models are cheaper; GPS and vision models cost more and save a day of installation — worth pricing before you commit to a wire layout. Compare robot mowers → Advertising — we may earn a commission.
Bookmark this before you start comparing models
Specifications change every product generation, and you will want to re-check these numbers against whatever is on offer when you actually buy. Press Ctrl + D — or ⌘ + D on a Mac.
Read before you buy
Twenty-five guides, specs decoded and real-world problems — see all guides →
The most expensive one is not the best
A family upgraded to a £1,400 flagship and could not see the difference. Why that was predictable.
FloorsCarpet homes need a different machine
Two neighbours bought the same vacuum. One was delighted, one returned it. The floors explain it.
DurabilityWhy vacuum necks break
A commercial machine from a global brand snapped at the neck within months. Nobody had misused it.
ErgonomicsYour height changes which vacuum suits you
Same machine, same reviews, opposite experiences. The variable nobody publishes is the user.
TroubleshootingWhy yours keeps getting stuck
Most robot vacuums end up in cupboards because the owner got tired of rescuing them.
SpecsPa and the suction myth
The number has tripled in three years. Your carpets have not changed.
Common questions
How many Pa do I actually need?
For hard floors and low-pile rugs, roughly 4,000–8,000 Pa is genuinely sufficient. Medium carpet benefits from 10,000–15,000. Thick or high-pile carpet with a heavy-shedding pet is the only common case where 20,000+ shows a real difference. Above that, brush design and number of passes matter far more than the headline figure.
Is Pa a reliable way to compare models?
Only loosely. Pa measures static pressure in a sealed test with no brush fitted, so it does not account for airflow, seal quality, brush design or how many passes the machine makes. Two vacuums with the same Pa can perform very differently on the same carpet.
Do I need a self-emptying dock?
It is the single feature most owners say they would not give up, because it turns a weekly chore into a monthly one. It costs more upfront and bags are an ongoing expense, so the honest answer is that it buys convenience rather than cleaning performance.
Will one robot handle a two-storey house?
Not on its own — none of them climb stairs. You either carry it between floors, in which case check the model stores multiple floor maps, or buy one per floor. This is worth deciding before you buy rather than after.
Does this site earn commission?
Yes, on some links, and they are labelled AD · PARTNER. The calculators are built to tell you when a cheaper model is sufficient, which frequently means recommending you spend less. That is deliberate.