Battery vs Gas: Efficiency & kWh Charging Cost
You're looking at a cordless saw and a gas saw side-by-side, and the price tags don't tell the whole story. The real difference comes down to what you'll spend every time you pull the trigger, which is exactly where energy efficiency ratings and battery kilowatt hour charging cost in cordless & gas chainsaws become the deciding factor between a bargain and a money pit.
Our research shows most homeowners pay around five cents per charge for a cordless saw, while a gas saw burns through roughly a dollar's worth of fuel every hour of heavy cutting. That gap adds up fast if you're processing firewood or clearing storm debris. Let's break down the actual numbers so you know which one fits your wallet and your workflow.
Quick Answer
Cordless chainsaws cost about $0.05 to $0.15 per hour to run, while gas saws run $0.75 to $1.50 per hour. Battery efficiency depends on watt-hours per charge and your local electricity rate. Gasoline contains far more energy per pound, but two-stroke engines waste most of it as heat.
For occasional use, battery wins on operating cost. For all-day cutting, gas remains cheaper overall despite higher fuel costs.
What You Actually Pay Per Hour: Gas vs Cordless
The daily cost difference is bigger than most guess. A cordless saw with a 5Ah, 56V battery holds about 280 watt-hours. At the average US electricity rate of $0.17 per kilowatt-hour as of 2026, a full charge costs roughly a nickel. A gas saw drinks about 0.8 liters per hour under load, which works out to roughly $0.84 per hour at current fuel prices. That's a 16x difference in hourly fuel cost.
But that nickel buys you maybe 30 minutes of runtime. Cutting all afternoon means swapping batteries and rapid charging, which draws power continuously. Our research across user reports and manufacturer specs shows the true cost per hour of cutting with battery saws lands around $0.10 to $0.15 when you factor in charging losses and multiple batteries. Gas still costs more per hour, just less dramatically than raw per-charge math suggests.
Keep the correct fluid level in mind – you're not just buying energy, you're buying time. A gas saw keeps running as long as you have fuel mix. A battery saw stops when the pack hits empty, and that replacement battery might cost $300 or more if you want a spare. The real question isn't just cost per hour; it's cost per cord of wood cut.
The Real Math on Efficiency and Charging Costs
Calculating Battery Cost Per Kilowatt-Hour
Every cordless chainsaw battery is rated in volts and amp-hours. Multiply them to get watt-hours, divide by 1,000 to get kilowatt-hours. That's what your electric bill cares about. For a 56V battery with 5Ah capacity, that's 280Wh or 0.28kWh. Multiply by your local rate, say $0.17, and you get $0.047 per charge.
Charging efficiency knocks that up slightly. No charger is 100% efficient; the battery management system and charger waste 5% to 15% as heat, especially during rapid charging. A 30‑minute rapid charge wastes more than an overnight trickle. So real cost per charge is closer to $0.055–$0.06. Over a hundred charges, you've spent maybe $6 on electricity, compared to $80 on gas for the same cutting time.
Voltage and amp‑hour ratings vary: 40V, 56V, 60V, 80V. Higher voltage doesn't mean higher efficiency—it lets the motor produce more power with less current, reducing heat losses. But total stored energy comes down to watt‑hours. Two batteries with the same watt‑hours cost the same to charge, regardless of voltage.
How Much Gas a Two-Stroke Really Drinks
Gas saws quote fuel consumption in liters per hour, but that changes with load. Idling sips fuel; buried in a 16‑inch oak log at full throttle, you might burn a full tank in 20 minutes. The EPA doesn't mandate fuel‑economy labels for small engines; you have to dig into the spec sheet for "fuel consumption at rated power."
Most 45cc–60cc gas saws drink between 0.5 and 1.5 liters per hour under typical working conditions. The 0.8 L/h figure is a solid average for a 50cc saw bucking medium hardwoods. At $4.00 per gallon, a liter costs about $1.05, so you're spending $0.84 per hour on fuel alone. That doesn't include two‑stroke oil, which adds another 2%–3%.
The efficiency gap comes down to thermodynamics. Gasoline holds roughly 9.7 kWh per liter, but a two‑stroke engine converts only about 25%–30% into mechanical work; the rest is waste heat, noise, and unburned hydrocarbons. An electric motor runs at 80%–90% efficiency, turning almost all battery energy into cutting power. So while gasoline packs more energy per pound, the saw that burns it wastes most of that potential.
Which Saw Makes Sense for Your Situation
Weekend Firewood and Storm Cleanup
If you cut a few cords a year, work in short sessions, and value quiet mornings, battery makes strong financial sense. The per‑hour energy cost is negligible. You don't need to winterize the fuel system or worry about stale gas gumming up the carburetor. Grab the saw, cut, then wipe it down and store the battery at about 50% charge in a cool garage.
The catch is runtime. A 5Ah battery gives maybe 20–40 minutes of actual cutting depending on wood and bar length. That's fine for pruning and limbing, but if you're bucking a whole oak, you'll want two or three batteries on hand. A rapid charger knocks recharge time to 30–45 minutes, so you can rotate packs. Expect to pay $250–$400 each for OEM packs.
For suburban or HOA neighborhoods, battery wins on noise alone. Gas saws hit 110 dB under load, loud enough to annoy neighbors and violate quiet‑hour ordinances. Battery saws run around 90–95 dB—more like a loud conversation—so you can cut early on Saturday without complaints. Routine upkeep is minimal: no air filters, spark plugs, or carb adjustments.
Daily Professional or Forestry Work
For arborists or loggers cutting six to eight hours straight, gas still dominates. You can carry a one‑gallon fuel can and cut continuously, swapping to a spare saw if needed. With battery, you'd need eight to twelve batteries per day, plus a generator to charge them in the field—thousands of dollars in packs and a heavy, noisy charging setup.
Energy density is the bottleneck. Gasoline holds about 40 times more usable energy per pound than lithium‑ion after accounting for engine efficiency. That's physics. For remote work where you pack in your gear, gas is the only practical option. The saw runs all day on a few gallons of mix; the batteries alone would weigh more than the gas saw and fuel combined.
Professional‑grade gas saws also deliver higher peak power for large‑diameter hardwoods—you can run a 28‑inch bar through old‑growth fir without bogging. Battery saws are catching up but are best suited for 16‑inch bars and below. The torque curve differs: electric delivers instant peak torque (great for limbing), but gas has a broader power band that keeps cutting through variable densities. If your living depends on the saw, gas remains the reliable workhorse despite higher fuel cost.
Frequently Asked Questions
How much does it cost to fully charge a cordless chainsaw battery?
A typical 5Ah, 56V battery holds about 0.28 kWh. At $0.17 per kWh, one full charge costs about $0.05. Rapid charging adds 5%–15% waste heat, pushing the real cost to roughly $0.06 per charge. You'll barely notice it on your electric bill.
How long does a battery chainsaw run per charge?
Runtime ranges from 15 to 45 minutes depending on battery size, bar length, and wood density. A 5Ah pack on a 16‑inch saw cutting softwood might last 35–40 minutes. Bucking hardwood drops that to 20–25 minutes. Cold weather also reduces runtime significantly.
Is gas or electric chainsaw cheaper to run per hour?
Electric is cheaper per hour—about $0.10–$0.15 versus $0.75–$1.50 for gas. However, gas saws run continuously without battery swaps. For a full day of cutting, you might spend $12 on gas versus $6 on electricity, but you'll need $500+ in spare batteries to match the gas saw's unlimited runtime.
What's more energy efficient for cutting firewood?
Electric motors convert about 85% of battery energy into cutting power. Two‑stroke gas engines convert only about 28%. So electric uses far less primary energy per cut. But the energy density of gasoline lets a gas saw run much longer on a single "tank" than a battery saw on one charge.
Can I use a gas chainsaw in a residential neighborhood?
Most cities have noise ordinances that limit gas saw use to daytime hours. Gas saws hit 110 dB, which carries through closed windows. Battery saws run at 90–95 dB and produce no fumes, making them the clear choice for suburban and HOA‑regulated areas. Check your local rules before buying.
