40 Volt Cordless Lawn Mowers: Runtime per Battery, Deck Sizes and Which Lawns They Suit

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A 40 volt cordless lawn mower is the sweet spot for most suburban lawns up to about a third of an acre: enough power to cut a 20- to 21-inch swath through normal grass, enough runtime from one or two packs to finish the job, and a price well below the 56V, 60V and 80V flagship platforms. Where it struggles is large yards, wet spring growth and steep hills, and knowing those limits is the key to buying the right one.

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#1 Pick

Greenworks 40V 16in Push Lawn Mower, 4.0 Ah Battery and Charger

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#2 Pick

MZK 40V 16-Inch 2-in-1 Lawn Mower, Brushless Cordless Push Mower

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#3 Pick

WORX Cordless Lawn Mower, 40V 14" 2-in-1 Grass Mower for 1/8 Acre, WG735

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#4 Pick

SEYVUM 40V 16" Cordless Lawn Mower with 2×4.0Ah Battery, 45L Collection Bag

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What 40V Means Compared With Other Voltages

Voltage on its own does not equal cutting power, but it sets the ceiling. Higher voltage lets a motor deliver the same wattage with less current, which means less heat and better performance in thick grass. The table puts the common classes side by side.

Lawn-size figures assume dry, regularly cut grass on mostly flat ground. Long or damp grass can cut coverage by a third or more.

The Main 40V Mower Families

Ryobi 40V HP

Ryobi’s 40V line is one of the broadest in the US, with push and self-propelled mowers in roughly 20- and 21-inch decks, and brushless HP models aimed at heavier grass. The batteries are shared with Ryobi 40V trimmers, blowers and chainsaws, which makes the platform attractive if you want a complete battery yard kit. Many kits ship with one pack; the self-propelled models benefit from a second.

Greenworks 40V

Greenworks covers the budget end of 40V with decks from around 16 inches up to 21 inches, push and self-propelled. The smaller decks are light and easy to lift and store vertically, which suits townhouse lawns. Greenworks also sells higher-voltage 60V and 80V lines, so check the voltage before buying extra packs.

Kobalt 40V

Kobalt’s 40V mowers, sold through home-improvement retail, typically come in 20-inch push and self-propelled versions with a solid steel or composite deck depending on model. The battery family is narrower than Ryobi’s but includes the core lawn tools.

Earthwise 24V and other low-voltage options

If your lawn is a small front patch, a 24V mower like those from Earthwise is lighter and cheaper, but its 13- to 17-inch deck and smaller pack mean more passes and less tolerance for overgrown grass. For anything larger than a postage-stamp lawn, 40V is the more comfortable minimum.

Runtime Math You Can Do Before Buying

Battery energy is voltage times amp-hours. A 40V 5.0 Ah pack holds 200 Wh. A 21-inch 40V push mower cutting normal grass typically draws something like 400 to 700 watts on average, more with mulching or tall grass.

• 200 Wh / 500 W average = 0.4 hours, or about 24 minutes of cutting.
• A 21-inch deck at a walking pace of 2.5 to 3 mph, with overlap and turns, covers roughly 15,000 to 20,000 sq ft per hour.
• 24 minutes therefore covers about 6,000 to 8,000 sq ft, or roughly 1/6 to 1/5 of an acre.

Self-propelled drive adds load, so expect 10 to 25 percent less coverage per pack. If your lawn is 10,000 sq ft, plan for two 5 Ah packs or one 6 Ah pack plus a short recharge.

Choosing a 40V Mower by Your Situation

Features That Matter More Than the Spec Sheet Suggests

• Brushless motor: holds speed better in dense grass and usually runs cooler, which stretches battery life.
• Single-lever height adjustment: much easier than four separate wheel levers when you change height seasonally.
• Dual battery ports: some 40V mowers hold two packs and switch automatically, removing the mid-mow battery swap.
• Vertical storage: a fold-flat handle and upright storage can save a lot of garage floor.
• Rear wheel size: 8- to 10-inch rear wheels roll better on bumpy lawns than 6- or 7-inch wheels.

Ownership Realities

Blade care

A sharp blade matters more on a battery mower than a gas one, because a dull blade tears grass and raises current draw. Sharpen or swap the blade at least once a season, more often on sandy soil. Remove the battery before touching the blade.

Battery life

Expect the original pack to deliver good capacity for several seasons if it is stored indoors over winter at partial charge. Replacement 40V packs commonly cost $100 to $250 depending on capacity, which is the main long-term running cost.

Common mistakes

• Cutting overgrown grass in one pass at the lowest height; raise the deck and take two passes instead.
• Leaving the pack in a hot shed or freezing garage.
• Assuming every 40V pack fits every 40V tool: Ryobi, Greenworks and Kobalt 40V batteries are not cross-compatible.

Bottom Line

A 40V cordless lawn mower is the right tool for small to medium yards when you want low maintenance and a shared battery platform. Match deck width and drive to your lawn size, buy enough watt-hours to finish in one session, and step up to 56-80V only if your lawn is large, hilly or consistently thick.