Ask ten brush cutter owners which is cheaper to run, petrol or battery, and you’ll get ten confident answers pointing in different directions — mostly because each is comparing their own usage pattern. Fuel and electricity prices also move, so rather than quote totals that will be out of date by next season, this page shows how to work out your own running cost, with worked examples whose assumptions are stated so you can swap in your own numbers.
Why purchase price is the wrong starting point
A mid-range petrol brush cutter and a mid-range battery brush cutter (bare tool plus one battery and charger) often land in a similar price band. From then on they diverge in what they cost to keep running, and that divergence decides the cheaper option over five years.
Petrol running cost breaks into three buckets: fuel, two-stroke oil, and servicing and consumables. Battery breaks into two: electricity for charging, and pack replacement when capacity fades. Line and blades cost about the same for either at an equivalent cutting width, so they’re left out.
Petrol: how to work out your fuel cost
Fuel consumption varies with engine size and load, and most manufacturers don’t publish a litres-per-hour figure, so measure your own: fill the tank, note the time, and refill after a typical session. Then:
annual fuel cost = litres per hour × hours per year × pump price
Worked example (assumptions, not quotes): a machine that burns 0.6 L an hour, used 40 hours a year, with petrol at £1.40 a litre, costs 0.6 × 40 × 1.40 = about £34 a year in fuel. At 15 hours a year the same machine costs about £13; at 200 hours, about £168.
Two-stroke oil
At 50:1 you add 20 ml of oil per litre of fuel (see the ratio chart), so the 24 litres in the example above need just under half a litre of oil a year — a small line item next to the fuel. The ratio still matters: too rich fouls plugs and carbons up the exhaust; too lean risks a seized piston, which costs far more than any oil.
Servicing and consumables
This is where petrol running cost really accumulates over time:
- a spark plug, air filter and fuel filter at the intervals in your maintenance schedule — cheap parts if you fit them yourself
- an annual service, free in labour if you do it yourself, or a dealer’s price if not (one UK retailer listed £72.00 including VAT in October 2026 — see service costs)
- every few years, carburettor or ignition work that a battery machine simply doesn’t have
Safety note. Never top up fuel on a hot engine — spilled fuel on a hot cylinder or muffler is a genuine fire risk. Let the machine cool for several minutes first, and always refuel outdoors away from ignition sources.
Battery: how to work out your electricity cost
A battery’s energy is its voltage times its amp-hours: a 36 V, 5 Ah pack holds 36 × 5 = 180 Wh, or 0.18 kWh. Charging losses add a little, so:
cost per full charge ≈ pack kWh × 1.1 × electricity price
Worked example (assumptions): a 0.18 kWh pack at 25p per kWh costs about 0.18 × 1.1 × 0.25 = 5p a charge. Even 100 full charges a season comes to about £5 — a rounding error next to petrol.
Servicing and consumables
Battery brush cutters strip out most petrol service items: no carburettor, plug, air filter or exhaust. What remains is gearbox grease, the cutting head or blade, fastener checks, and on brushed motors eventual brush wear (brushless motors avoid that).
Battery pack replacement — the number that decides it
Lithium-ion packs lose capacity with every charge cycle, with heat and with age. After a few hundred full cycles many packs have lost enough runtime to be worth replacing even though they still work, and a replacement pack is a large cost relative to the machine — often a substantial fraction of what the whole kit cost. A light domestic user doing 15-20 charges a year may never need one inside five years; a heavy user charging several times a week may need one within two or three seasons.
Safety note. Store lithium packs part-charged rather than full over winter, don’t leave them on charge unattended for long periods, and take a swollen or damaged pack out of service immediately.
Putting it together over five years
| Usage | Petrol | Battery | Usually cheaper to run |
|---|---|---|---|
| Light domestic (around 15 hours a year) | Small fuel bill plus servicing, which dominates | Pennies in electricity; pack likely to outlast five years | Battery |
| Moderate domestic (around 40 hours a year) | Fuel bill grows, servicing the same | Still low electricity cost; one replacement pack possible | Battery, by a narrower margin — depends on pack price |
| Heavy or professional (around 200 hours a year) | Fuel becomes the big cost | Electricity still cheap, but several replacement packs | Roughly even; often tilts to petrol on pure running cost |
The pattern holds whatever prices you plug in: battery wins at light and moderate use because you may never buy a second pack, and at professional duty the cost of replacement packs catches up with petrol’s fuel and servicing. Petrol versus battery more broadly — power, noise, weight — is compared in petrol vs battery brush cutters.
What actually shifts the answer for you
- Count your real annual hours. Most domestic users overestimate them — track one season before deciding.
- Check whether you’re already on a battery platform. If you own other tools on the same battery system, a bare-tool brush cutter changes the maths strongly in battery’s favour.
- Price a replacement pack before you buy. Pack prices vary a lot between platforms, and this one number decides the five-year comparison more than any other.
- Factor in your maintenance habits. A well-kept petrol machine costs noticeably less to run than a neglected one.
- Re-run the sums when prices change. The formulas above take a minute with your own pump price and electricity tariff.
Quick checklist before deciding
- Estimate your genuine annual cutting hours
- Time a tank of fuel on your own machine to get litres per hour
- Multiply by your pump price, and add servicing
- Work out pack kWh × your tariff for the battery option
- Get an actual replacement pack price for the model you’re considering
- Check whether you already own compatible batteries
- Re-run the comparison if your usage changes (for example, taking on paid work)