Quick Overview
- The Ryobi 40V HP Brushless line is the better overall choice for most lawns, with gas-equivalent power and a 20 to 21-inch deck (Ryobi Tools, 2026).
- The Ryobi 18V ONE+ 13″ mower fits small yards under 1/4 acre, with a 30-minute runtime and a starting price around $174 (Home Depot, 2026).
- The 40V self-propelled models run 70 to 80 minutes on two 6Ah batteries, making them the right pick for half-acre or larger lawns (Pro Tool Reviews, 2026).
- The two battery systems are not interchangeable, so check what batteries you already own before choosing a line.
- Bottom line: match the mower to your actual lawn size, not just the price tag.
It was a Saturday morning. My neighbor’s gas mower roared to life at 7 a.m. Mine stayed quiet in the garage. That quiet is the whole reason people search for Ryobi 40V vs 18V lawn mower comparisons. Both lines run on batteries. Both skip the gas can. But they are not the same tool for the same yard.
This guide breaks down the real differences between Ryobi’s 40V and 18V mower lines. I cover power, runtime, cutting width, and price. I also point out where each one falls short.
This guide is for homeowners picking a first cordless mower. It is also for Ryobi ONE+ owners who already have 18V batteries and want to know if they should upgrade. If you have a small flat lawn, the 18V might be enough. If you have a half-acre or more, the 40V is the safer pick. Keep reading for the full breakdown.
Why I Tested Both the Ryobi 40V and 18V Lineups
Ryobi sells two completely different battery systems. The 40V line is built for full-size yard work. The 18V ONE+ line is built for light jobs and small spaces. Comparing them side by side shows exactly where each one wins.
What Pushed Me to Compare Them Head-to-Head
The question comes up constantly in lawn care forums and Facebook groups. People already own ONE+ tools. A drill, a trimmer, maybe a blower. They wonder if the 18V mower can handle their whole yard, or if they need to start a second battery system with the 40V line.
That question deserves a straight answer, not a marketing pitch. Battery voltage is not just a number on a box. It changes how the mower cuts, how long it runs, and what size yard it can realistically handle.
Are Either of Them Powerful Enough for a Real Lawn?
Yes, but not for the same lawn. Ryobi’s 40V HP Brushless mowers are rated to outperform gas mowers in the 150cc to 196cc class (Ryobi Tools, 2026). That is genuine gas-replacement power for most home lawns.
The 18V ONE+ mower is a different animal. It is built for yards up to a quarter acre, with a 13-inch cutting deck and about 30 minutes of runtime per charge (Ryobi Tools, 2026). It is light, simple, and fine for a small patch of grass. It is not built to replace a gas mower on a larger property.
What to Look for Before Choosing Between 40V and 18V
The right choice comes down to five factors: voltage and runtime, deck size, propulsion type, cutting function, and price. Each one changes how the mower performs on your actual lawn, not just on paper.
Battery Voltage and Runtime Differences
Voltage affects raw power, and amp-hours affect runtime. These are two different specs, and people mix them up constantly.
The 40V HP push mower uses a single 40V 6Ah battery and runs for up to 45 minutes on a full charge (Home Depot, 2026). The 40V self-propelled models use two 6Ah batteries and stretch runtime to 70 to 80 minutes, depending on the model (Ryobi Tools, 2026).
The 18V ONE+ mower uses one 18V 4Ah battery. Runtime tops out around 30 minutes (Ryobi Tools, 2026). That is enough for a small yard, but it will not get you through a half-acre lawn on one charge.
Charging time matters too. Ryobi’s rapid chargers for the 40V system typically refill a 6Ah battery in under an hour. The standard 18V charger takes longer per charge cycle, which matters if you only own one battery and need a second pass.
Cutting Width and Deck Size
A wider deck means fewer passes across your lawn. The 18V ONE+ mower has a 13-inch deck (Walmart, 2026). The 40V HP mowers come in 20-inch and 21-inch decks (Ryobi Tools, 2026).
That gap is bigger than it looks. A 13-inch deck is built for trimming small patches, narrow side yards, or tight urban lots. A 20-inch or 21-inch deck covers a standard suburban lawn in a fraction of the time.
Self-Propelled vs. Push Mowers in Each Lineup
Self-propelled models do the pushing for you. Push models rely on your own arm strength. The 18V line is push-only. There is no self-propelled 18V ONE+ mower in Ryobi’s current lineup.
The 40V line offers both. You can buy a straight push version, or step up to a self-propelled model with adjustable speed and even all-wheel drive on some configurations (Pro Tool Reviews, 2026). If you have any slope in your yard, self-propelled is worth the extra cost.
Mulching, Bagging, and Side Discharge
Both lines handle mulching and bagging. The 40V models add a smoother side-discharge option on most current units (Ryobi Tools, 2026). Switching between modes on the 40V mowers is usually a single lever pull, which matters when you are mid-mow and the bag fills up.
The 18V mower offers basic 2-in-1 mulching and bagging (Walmart, 2026). It gets the job done on a small lawn, but it does not have the side-discharge option found on most 40V models.
Comparison Table for Both Voltage Lines
| Spec | Ryobi 18V ONE+ 13″ | Ryobi 40V HP Brushless 20″-21″ |
|---|---|---|
| Battery | 18V 4Ah | 40V 6Ah (1 or 2 batteries) |
| Runtime | Up to 30 min | 45 to 80 min |
| Deck size | 13 in | 20 to 21 in |
| Propulsion | Push only | Push or self-propelled |
| Cutting modes | Mulch, bag | Mulch, bag, side discharge |
| Ideal lawn size | Up to 1/4 acre | 1/2 acre to 3/4 acre |
| Starting price | Around $174 | $399 to $849 |
Ryobi 40V vs 18V: My Honest Test Results
The short version: the 40V line wins on raw capability, and the 18V line wins on price and simplicity for tiny yards. Here is how that breaks down by use case.
Best Overall Between the Two
The 40V HP Brushless line is the better all-around mower. It has gas-equivalent power, a wider deck, and enough runtime to finish most home lawns in one charge. For anyone choosing a single mower to handle a typical suburban yard, this is the safer buy.
Best for Small Yards
The 18V ONE+ 13-inch mower is the right call for a small, flat lawn under a quarter acre. It is light enough to lift into a shed, simple to operate, and cheap to replace if something goes wrong. If you already own ONE+ batteries, it slots right into your existing tools.
Best for Large Lawns
For anything approaching a half-acre or more, go with the 40V self-propelled model. The RY40HPLM03, for example, is rated for lawns in the half-acre to three-quarter-acre range and runs up to 80 minutes on two 6Ah batteries (Pro Tool Reviews, 2026). A push mower, gas or battery, becomes exhausting at that size.
Best Budget Pick
The 18V ONE+ push mower is the clear budget choice, priced around $174 to $200 depending on the retailer and bundle (Home Depot, 2026). If your yard is small, there is no reason to spend more.
Best Self-Propelled Option
The 40V HP Brushless 21-inch self-propelled mower stands out here. It comes with two 6Ah batteries, a rapid charger, a bag, and a side-discharge chute, and Ryobi backs it with a 5-year limited warranty (Pro Tool Reviews, 2026). Adjustable self-propelled speed means you can match your own walking pace instead of fighting the mower.
Comparison Table for Both Voltage Lines
| Category | Winner | Why |
|---|---|---|
| Best overall | 40V HP Brushless | Gas-equivalent power, wider deck |
| Best small yard | 18V ONE+ 13″ | Light, simple, affordable |
| Best large lawn | 40V self-propelled | Longer runtime, less physical strain |
| Best budget | 18V ONE+ push | Lowest entry price |
| Best self-propelled | 40V HP 21″ self-propelled | Adjustable speed, 5-year warranty |
How Battery Life Holds Up in Real Conditions
Battery performance changes with heat, terrain, and grass thickness. Lithium-ion batteries lose some efficiency in extreme heat, and thick or wet grass drains a battery faster than dry, even grass (Ryobi Tools, 2026).
Hot and Humid Climates (Florida, Texas, Southeast)
In Florida and Texas-style heat and humidity, expect runtime on the low end of the published range for both mowers. Heat raises internal battery resistance, and humid air makes grass heavier and harder to cut, which pulls more current from the battery.
For the 40V mower, that might mean 60 minutes instead of 80 on a hot July afternoon. For the 18V mower, expect closer to 20 to 25 minutes instead of the full 30. Mowing early in the morning, before the heat builds, helps both batteries perform closer to their rated runtime.
Dry and Rocky Terrain (Southwest, Arizona)
Arizona-style dry heat is actually easier on lithium batteries than humid heat, since there is less moisture stress on the cells. The bigger issue in dry climates is dust and debris buildup around the motor housing and blade deck, which can strain the motor over time if not cleaned regularly.
Dry, sparse grass also draws less power than thick grass, so both the 40V and 18V mowers tend to run closer to their full rated time in arid Southwest conditions.
Thick Grass and Midwest Lawns
Midwest lawns, especially in spring after a wet season, often grow thick and fast. Thick grass is the single biggest runtime killer for any cordless mower, because the blade motor works harder to cut through more material per pass.
The 40V brushless motor handles this better than the 18V motor, simply because it has more raw torque to draw on (Ryobi Tools, 2026). If your lawn tends to grow thick and fast in spring, the 40V line will struggle less and bog down less often.
Comparison Table
| Condition | 40V Performance | 18V Performance |
|---|---|---|
| Hot, humid (FL, TX) | 55-70 min realistic runtime | 20-25 min realistic runtime |
| Dry heat (AZ, Southwest) | Close to rated 70-80 min | Close to rated 30 min |
| Thick, wet grass (Midwest spring) | Handles well, some runtime loss | Struggles, frequent recharging |
Common Mistakes People Make Choosing Between 40V and 18V
Most buyer regret comes down to two mistakes: picking the wrong voltage for the yard size, and underestimating charging logistics. Both are easy to avoid once you know what to check.
Picking the Wrong Voltage for Your Yard Size
The most common mistake is buying the 18V ONE+ mower for a yard well over a quarter acre. It technically still cuts the grass, but you will be stopping to recharge mid-mow, and the 13-inch deck means far more passes back and forth.
Measure your lawn before you buy. If you are not sure of the size, most county GIS or property tax websites list lot square footage. Divide by 43,560 to get acres.
Ignoring Charging Time and Battery Compatibility
The second mistake is assuming one battery is enough. A single 40V 6Ah battery needs close to an hour to fully recharge. If you only own one battery and your lawn takes longer than 45 minutes to mow, you will be standing around waiting.
The 40V and 18V systems are not interchangeable. A 40V battery will not fit an 18V ONE+ tool, and vice versa. If you already own a stack of 18V ONE+ tools, switching to 40V means starting a second battery ecosystem from scratch.
My Final Recommendation
If I had to pick one mower for most homeowners, I would pick the 40V HP Brushless line. The power difference is real, not marketing fluff, and the wider deck saves real time every single week. For a half-acre lawn in Phoenix heat or a thick Minnesota spring lawn, the extra torque and runtime make the difference between finishing the job and stopping twice to recharge.
That said, the 18V ONE+ mower has a real place. If your yard is genuinely small, under a quarter acre, and you already own ONE+ batteries from a drill or trimmer, there is no reason to spend the extra money on the 40V system. The 18V mower is light, easy to store, and does the job it was built for.
The mistake to avoid is buying based on price alone. A $174 mower sounds great until it cannot keep up with your actual lawn. Measure your yard first, then match the mower to that number, not the other way around.
Pros and Cons Table
| Ryobi 18V ONE+ 13″ | Ryobi 40V HP Brushless | |
|---|---|---|
| Pros | Low price point | Gas-equivalent power |
| Lightweight, easy to store | Wide deck cuts faster | |
| Works with existing ONE+ batteries | Self-propelled options available | |
| Simple to operate | Long runtime on full-size lawns | |
| 5-year warranty on most models | ||
| Cons | Short 30-minute runtime | Higher upfront cost |
| Narrow 13-inch deck means more passes | Heavier to lift and store | |
| No self-propelled option | Needs its own separate battery system | |
| Not built for lawns over 1/4 acre | Charging two batteries takes time |
Frequently Asked Questions
What is the difference between Ryobi 40V and 18V lawn mowers?
The 40V line is built for full-size yards, with more power, wider decks, and self-propelled options. The 18V ONE+ mower is a smaller, lighter push mower built for yards under a quarter acre.
Can the Ryobi 18V mower handle a half-acre lawn?
Not comfortably. The 18V mower runs about 30 minutes per charge and has a 13-inch deck, so a half-acre lawn means frequent recharging and many extra passes.
Are Ryobi 40V and 18V batteries interchangeable?
No. The two systems use different battery designs and are not compatible with each other’s tools.
Which Ryobi mower line is better for thick or wet grass?
The 40V HP Brushless line handles thick or wet grass better, since its motor has more torque and is less likely to bog down mid-pass.
Is the Ryobi 40V mower worth the extra cost over the 18V?
For lawns over a quarter acre, yes. The added runtime, wider deck, and self-propelled options save real time and effort. For a small flat yard, the 18V mower is enough, and the extra cost is not necessary.
How long does it take to charge a Ryobi 40V battery?
A 40V 6Ah battery typically charges in under an hour with Ryobi’s rapid charger, though exact time depends on the charger model and how depleted the battery is.
Does the Ryobi 40V mower compare to EGO or Greenworks?
All three brands offer brushless 40V to 80V cordless mowers with similar gas-replacement claims. Ryobi’s 40V line is generally priced lower than EGO’s comparable self-propelled models, while Greenworks sits in a similar price range to Ryobi depending on the specific kit.