A battery mower costs around 20p to run for a typical mow. A petrol mower can cost six to eight times that in fuel alone, before servicing. Neither number decides which one to buy. That comes down to how big the garden is, how much time there is for charging or refuelling, and whether the lawn has slopes, beds or obstacles a mower has to work around. This guide starts with garden size, because that’s the decision most buying guides skip past on their way to comparing brands.
Start with your garden’s size, not the brand
Garden size sets the shortlist of realistic mower types before anything else does.
These bands come from Ron Smith & Co’s garden machinery sizing guide. Most UK terraced and semi-detached back gardens sit well inside the small band. As a rough test, a lawn that takes more than 45 minutes to walk end to end while mowing is probably medium or pushing into large, pacing it out roughly beats guessing, and a property’s plot size is usually listed on the original sales listing or Land Registry title plan if it’s worth checking properly.
The mistake worth naming here: buying on a discount, or a brand already trusted for something else, and only checking the cutting width against the actual garden afterwards. A 30cm deck on a 900m² lawn turns a Saturday job into most of the weekend. A 50cm deck shoehorned into a small, fiddly back garden with raised beds is wrong in the other direction, too wide to get between obstacles without doubling back constantly.
What corded, battery and petrol mowers actually cost
Purchase price and running cost don’t move together in the same direction, which is where most of the confusion in this decision comes from.
| Type | Typical price | Ongoing cost beyond electricity or fuel |
|---|---|---|
| Corded electric | £120–£150 (budget hover models from around £75) | None |
| Battery (cordless) | £350–£500 | Battery replacement, roughly £150 a pair every 3–5 years |
| Petrol | £350–£550 | Servicing, around £75–£90 a year |
| Ride-on | £1,200–£5,000+ | Servicing, higher fuel use |
| Robot | From around £600 (some budget models under £400), into the thousands | None beyond electricity |
Prices are Which?’s tested price ranges, and this comparison is built from published specifications and current UK pricing, not hands-on testing.
At the current Ofgem price cap rate of 26.11p per kWh for a typical dual fuel Direct Debit customer (1 July to 30 September 2026, rising to 26.32p from 1 October), a corded electric mower’s running cost is straightforward to work out. Corded mowers sold by UK retailers typically range from 1000W to 1800W:
| Mower wattage | Cost per hour | Cost for a 30-minute mow |
|---|---|---|
| 1000W | 26p | 13p |
| 1600W | 42p | 21p |
| 1800W | 47p | 24p |
Battery mowers land in a similar range once charging losses are counted. Ideal Home’s comparison puts a typical full charge at around 20p to 23p, for roughly the same 30 to 40 minutes of cutting time before a recharge is needed.
Petrol changes the maths, and not in petrol’s favour. A typical domestic push petrol mower burns roughly a litre of fuel an hour, though that varies a lot by engine size and how overgrown the grass is. At 161.12p a litre, the UK average price for unleaded in the week of 17 August 2026, that’s around £1.60 an hour in fuel alone, before the £75–£90 a year most petrol mowers need in servicing. Fuel prices move constantly, so treat that figure as a snapshot rather than a fixed number.
Corded electric: best for small, flat, easy-access gardens
Unlimited runtime, the lightest of the three to push, and the cheapest to buy and run. The catch is the cord itself: it needs a nearby outdoor socket, careful cable management, and a garden without hedges or borders that snag a trailing lead. It’s a poor fit for anything bigger than one extension lead can comfortably reach.
Battery (cordless): the middle ground, if the runtime is honest
No cord to manage, but battery mowers vary a lot in how long they actually run. Limited runtime is the trade-off most comparisons flag as the real catch, not weight or price, so it’s worth checking a specific model’s runtime against the garden’s actual size rather than assuming “cordless” solves the size question by itself.
Petrol: for larger or uneven gardens, at a real ongoing cost
More power, and copes better with longer grass and slopes than an electric mower will. The trade-off is fuel storage, an annual service, and a heavier, louder machine to push and manoeuvre. On a small garden, the extra power goes unused and the servicing cost isn’t earned back by the area being cut.
Cutting width and manoeuvrability matter as much as square metres
A garden’s square footage sets the mower type, but its shape and obstacles can knock that recommendation down a size band.
Narrow side access, raised beds, borders and trees favour a narrower deck and a lighter mower, even in a garden that measures out as medium by the table above, because working around obstacles matters more than covering the area in fewer passes. A wide-decked mower that’s brilliant on open lawn turns any garden broken up by borders, a washing line post or a trampoline into a three-point turn every few metres.
Slopes add a second complication. Heavier mowers, most petrol models and some battery ones, are harder to control and push uphill. Self-propelled versions solve this but add weight and price on top of whichever type was already chosen.
Anyone still deciding on the lawn itself rather than what cuts it, what turf actually costs to lay is worth reading before this one, since the mower question only comes after there’s grass to mow.
When a push mower stops making sense
Above roughly 1,000m², pushing any mower becomes the real cost, in time and effort rather than money.
At 1,000m² (roughly a quarter of an acre), a ride-on mower is worth considering. By 2,000m² (about half an acre), it’s a clear yes, according to Ron Smith & Co’s sizing guide. Ride-on mowers run from £1,200 to £5,000 or more.
Robot mowers are the other option at this end, and a genuinely different trade-off: near-zero ongoing labour, for running costs Expert Reviews puts at just a few pounds a month, against a higher upfront price of around £600 upward, with some budget models under £400. A robot mower is the closest lawn care gets to a fit-and-forget appliance, provided the garden itself cooperates. An open lawn with a clean perimeter suits one well. A garden broken into odd-shaped sections by paths, a shed and several beds is a fussier and more expensive install.
If a mower isn’t actually the right call
Not every garden needs a mower at all, which is either liberating or slightly sad depending on how much a Saturday morning behind a mower is actually enjoyed. For a very small, awkward or low-priority lawn, artificial grass removes the mowing decision entirely, at a materials cost that’s roughly equivalent to several years of mower ownership paid upfront. It’s worth reading if a mower increasingly looks like more hassle than the lawn justifies.
Hiring a local gardener or mowing service is the other route for anyone not planning to do this themselves. Costs vary a lot by region and lawn size, so it’s worth getting a couple of local quotes rather than assuming a single UK-wide figure means much either way.
Already decided on a brand?
Two mower brands get searched by name often enough on this site to be worth their own dedicated reviews, so there’s no need to repeat a full buying-guide philosophy twice.
If Qualcast’s range already looks like the right price and cutting width, the full Qualcast lawn mower range compared goes through the corded, cordless and petrol models by spec. McGregor’s range gets the same treatment in the McGregor lawn mower buying guide.
Once the mower’s chosen and the season’s done, grass clippings baked onto a mower deck or a patio are a separate cleaning job. The Karcher K3 review covers one widely bought pressure washer for that.
Frequently asked questions
How often should I mow my lawn?
According to RHS guidance on lawn mowing, an ordinary lawn needs mowing weekly through summer, dropping to fortnightly during drought, and fortnightly to weekly in spring and autumn depending on growth. Winter mowing is rarely needed. Whatever the season, the RHS’s rule is to never remove more than a third of the grass height in a single cut.
What size lawn mower do I need?
As a starting point: a 30–40cm cutting width for a garden up to 500m², 41–49cm for 500–1,000m², and 50cm or more above that. Garden shape can shift this down a band, a narrow or obstacle-heavy garden often suits a smaller deck than its raw square metreage suggests.
Is a battery mower powerful enough for a medium or large garden?
It depends on the model’s actual runtime against the garden’s size, and on how long the grass is allowed to get between cuts. Long, overgrown grass is harder on a battery mower’s charge than grass mowed on the RHS’s regular weekly schedule, so a battery mower and a lapsed mowing routine are a worse combination than a battery mower and a lawn that gets cut on time.
Do I need a wider cutting deck for a bigger garden, or just more time?
A narrower deck on a larger, open, obstacle-free garden still works, it just means more passes. Past medium size, most buyers move to a wider deck or a self-propelled model anyway, because the extra time per mow adds up quickly once the garden crosses into the medium-to-large band.
