Cordless vs Gas Chainsaw: Volts & Amp Hours

If you're shopping for a chainsaw, you've probably stared at specs like "40V, 5Ah" on a battery model or "50cc" on a gas one, and wondered how they actually compare. The short answer to how much electrical power voltage and battery amp hours in cordless & gas chainsaws is this: voltage and amp-hours tell you the battery's energy capacity (in watt-hours), while gas power is measured by engine displacement in cubic centimeters (cc). A 40V, 5Ah battery gives you 200 watt-hours of stored energy, which roughly matches the cutting capability of a 30, 35cc gas engine for light- to medium-duty work, but runtime and torque delivery are very different stories.

Once you move past the spec sheet, you realize that voltage affects torque, amp-hours determine how long you can cut, and displacement dictates peak power. In our research, we've seen that a 16-inch bar is the crossover point where both types compete well, above that, gas usually pulls ahead. And a critical factor many buyers overlook: the actual watt-hour number (volts × amp-hours) is the only honest measure of battery energy.

So let's break down each spec, what it means for your arm and your wallet, and which saw genuinely fits your yard or your livelihood.

Cordless vs. Gas: Voltage & Amp-Hours vs. Displacement

Let's cut through the marketing. For cordless saws, you'll see two numbers on the battery: voltage (V) and amp-hours (Ah). Multiply them, that's watt-hours (Wh), the total energy in the battery.

A 40V × 5Ah = 200Wh. A 60V × 4Ah = 240Wh. That's your true fuel tank size.

Voltage affects motor torque; higher voltage pushes the motor harder, which gives you better chain speed under load. Amp-hours affect runtime, more Ah means more minutes of cutting before you plug in.

For gas saws, the key spec is engine displacement in cubic centimeters (cc). Displacement is the volume of the cylinder. More cc generally means more horsepower and torque, but it also adds weight and fuel consumption.

A 30cc gas saw is entry-level; 50cc is the professional sweet spot for felling medium trees; 70cc+ is for serious logging. The comparison isn't direct, but industry data suggests a 40V brushless saw performs like a 30, 35cc gas engine in most cutting tasks, while an 80V system can rival a 45, 50cc gas saw.

When you're comparing, always convert to watt-hours for battery, that's the only honest measure. And for gas, don't just look at peak HP; check the torque curve (often not published) because that determines how it behaves in a heavy cut. As of 2026, most major manufacturers like Stihl and Husqvarna offer both types, so the choice isn't about brand loyalty, it's about the numbers that matter for your specific cuts.

What That Actually Means for Cutting: Runtime, Torque, and Bar Length

Here's where specs turn into sweat. Runtime on a cordless saw is the most common worry. A 4Ah battery on a 40V saw typically gives 20, 30 minutes of active cutting under moderate load.

Bump that to a 6Ah and you're closer to 40, 45 minutes. But that's under ideal conditions, dull chains, hardwoods, or cold weather (which saps lithium-ion performance) can cut runtime in half. Always buy a second battery if you plan more than light pruning; aggregate reviews show that's the number one regret among first-time buyers.

Torque is the other big factor. Voltage determines the motor's peak torque, but brushless motors deliver it more efficiently than brushed ones. In practice, a 60V brushless saw will power through a 12-inch oak log without bogging down, while a 40V model might stall on the same cut.

Gas engines have a different torque curve, they deliver peak torque at higher RPMs, so you need to rev them up. That's why gas saws feel more "grunty" once they're spinning, but they also require you to keep the throttle wide open.

Bar length ties directly to power. A 16-inch bar is the sweet spot for cordless saws with 40, 60V systems. Go to 18 inches and you'll want at least 60V or a 45cc gas engine.

For 20 inches, you're in pro gas territory, 50cc and up, or top-tier electric like an 80V model. In our analysis of user feedback, most homeowners never need more than a 16-inch bar; anything longer adds weight and reduces maneuverability without a real benefit for typical yard work.

The Hidden Costs: Battery Life, Gas Mixing, and Maintenance

The sticker price is only the beginning. Cordless saws seem cheaper upfront, but battery replacement is a hidden expense. Lithium-ion batteries degrade over time, you'll lose about 20% capacity after 300, 500 charge cycles, which for a heavy user is about 2, 3 years.

A replacement 5Ah battery can cost $150, $200, so factor that in. Also, you need to store batteries at 50, 80% charge in a cool place; leaving them fully discharged or in a hot garage kills them fast.

Gas saws have their own maintenance maze. You're mixing fuel and oil (typically 50:1 ratio), and ethanol-blend gasoline is the enemy, it gums up carburetors if left sitting for more than a month. You'll clean air filters, replace spark plugs, and occasionally rebuild the carburetor.

Over a five-year period, maintenance on a gas saw can exceed the cost of a new battery, especially if you don't run it dry for winter storage. The flip side: gas saws don't have battery degradation; they'll run indefinitely as long as you maintain them.

Choose cordless if you value convenience and have small to medium jobs. Choose gas if you cut frequently or need to run all day without waiting for a charge. But remember: a gas saw that's not maintained properly becomes a paperweight faster than a dead battery.

The Bottom Line: Which Chainsaw is Best for You?

There's no universal winner, it's about your cutting reality. If you're a homeowner with a suburban lot, occasional storm cleanup, and a few trees to prune, a cordless 40V, 56V saw with a 16-inch bar and a spare battery is your best bet. It starts instantly, runs quietly (your neighbors will thank you), and requires almost no upkeep beyond keeping the chain sharp and the bar oiled.

In our research, models from Ego and Greenworks consistently get high marks for reliability and runtime.

If you're a rancher, a tree service pro, or you heat your home with firewood, you need gas. A 50cc, 60cc saw with an 18, 20 inch bar will fell and buck hardwoods all day without battery anxiety. Stihl and Husqvarna dominate this space for good reason, their engines are bulletproof and parts are widely available.

You'll pay more for maintenance, but you'll never be stranded mid-cut with a dead battery.

For the in-between, say, a large property with occasional big jobs, consider a 60V, 80V cordless saw with a high-capacity battery (8Ah or more). These can handle a 16, 18 inch bar and give you enough runtime for a few hours of intermittent cutting. Just keep a second battery charged.

And if you're on the fence, rent both types for a weekend. Real-world experience beats any spec sheet.

Quick Answers: Power, Runtime, and Buying Questions

How much voltage do I need for a 16-inch bar?

For a 16-inch bar, you'll want at least 40V in a cordless saw and preferably a brushless motor. A 60V system gives you more headroom for hardwoods. In gas, 30, 35cc is adequate, but 40cc is safer for frequent use.

How long does a 5Ah battery last on a chainsaw?

It depends on the load and bar length. On a 40V saw with a 16-inch bar cutting softwood, you'll get 25, 35 minutes of actual cutting. In hardwood or with a dull chain, expect 15, 20 minutes.

Always buy a spare if you need more than light trimming.

Is a cordless chainsaw as powerful as a gas one?

For a given size, no, cordless typically maxes out around 45, 50cc equivalent. However, for 90% of homeowner tasks, a 60V cordless saw has enough torque and chain speed to outperform a 35cc gas saw, and it's quieter and easier to start.

Can I use any battery brand with any chainsaw?

No, battery platforms are proprietary. If you already have a brand's tools, say, DeWalt, Makita, or Milwaukee, look for their chainsaw that uses the same battery system. That saves you money and keeps your battery ecosystem consistent.

What's the best way to extend battery life?

Store batteries at 50, 80% charge in a cool, dry place. Avoid full discharges; recharge when they hit 20%. Don't leave them on the charger after they're full.

And keep them above freezing, cold lithium batteries lose capacity temporarily and permanently if stored below -20°C.