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Battery Mower Runtime Calculator: How Much Lawn Per Charge

Last updated Researched from specs, manuals and owner reviews, not tested in person

Quick answer

Multiply volts by amp hours to get watt-hours, then allow about 20 watt-hours per 1,000 square feet for a 21 inch self-propelled mower in normal grass. A 56V 7.5 Ah battery (420 Wh) cuts about 21,000 square feet, just under half an acre, per charge, while a 40V 4 Ah battery (160 Wh) covers about 8,000 square feet.

Battery mowers are sold by voltage and amp hours, but the useful number is watt-hours, the energy in the pack, because it decides how much lawn you cut per charge. Enter your lawn size, battery, deck width and grass conditions, and the calculator estimates square feet per charge, minutes of cutting and how many batteries your lawn needs. Maker runtime claims are listed below for comparison. Weighing battery against gas on total cost? Use the gas vs battery cost calculator.

Battery mower runtime calculator

Coverage per charge

21,000 sq ft

Battery mowers with the runtime you need

Top matches update when you calculate.

On this page
  1. How much lawn can a battery mower cut per charge?
  2. What runtimes do battery mower makers claim?
  3. How is battery mower runtime calculated?
  4. How many batteries do I need for my lawn?
  5. Should I stay on one battery platform?

How much lawn can a battery mower cut per charge?

Estimated coverage per charge, 21 in self-propelled
BatteryEnergySq ft, normal grassSq ft, tall or thickAcres, normal
40V 4 Ah160 Wh8,0005,7140.18
40V 6 Ah240 Wh12,0008,5710.28
56V 4 Ah224 Wh11,2008,0000.26
56V 5 Ah280 Wh14,00010,0000.32
56V 7.5 Ah420 Wh21,00015,0000.48
56V 10 Ah560 Wh28,00020,0000.64
60V 5 Ah300 Wh15,00010,7140.34
80V 4 Ah320 Wh16,00011,4290.37

What runtimes do battery mower makers claim?

Manufacturer runtime and acreage claims from the product listings, against this calculator's normal-grass estimate for the included battery.

Maker claims compared with estimate
MowerIncluded batteryMaker runtimeMaker rated areaOur estimate
EGO POWER+ LM2206SP 22 in. Aluminum Deck Self-Propelled Mower Kit56V x 10 Ah = 560 Wh70 minNot listed0.61 acres
EGO POWER+ LM2135SP 21 in. Select Cut Self-Propelled Mower Kit56V x 7.5 Ah = 420 Wh60 minNot listed0.48 acres
Greenworks 80V 25 in. Self-Propelled Mower Kit80V x 4 Ah = 320 WhNot listed0.75 acres0.31 acres
Greenworks 80V 21 in. Self-Propelled Mower Kit80V x 4 Ah = 320 WhNot listed0.5 acres0.37 acres
WORX WG760 40V 21 in. 3-in-1 Self-Propelled Mower40V x 5 Ah = 200 WhNot listed0.5 acres0.23 acres
EGO POWER+ LM2114 21 in. Push Mower Kit56V x 6 Ah = 336 Wh55 minNot listed0.39 acres
Greenworks 60V 21 in. Push Mower Kit60V x 5 Ah = 300 WhNot listedNot listed0.34 acres

How is battery mower runtime calculated?

  • Watt-hours = battery volts x amp hours. A 56V 5 Ah pack holds 280 Wh; a 60V 5 Ah pack holds 300 Wh.
  • Energy per 1,000 sq ft = about 20 Wh for a 21 inch self-propelled deck, scaled up for wider decks and by 1.4 for tall or thick grass, plus self-propel and bagging load.
  • Coverage per charge = watt-hours / energy per 1,000 sq ft x 1,000.
  • Minutes = coverage / cutting rate, using about 0.43 acres per hour for a 21 inch mower at 3 mph.

Voltage alone does not tell you runtime: an 80V 2 Ah pack holds 160 Wh, the same as a 40V 4 Ah pack. Compare watt-hours across brands. Most modern mowers also run their blade faster in thick grass automatically, which is why runtime claims vary so much with conditions.

How many batteries do I need for my lawn?

Divide your lawn area by the coverage per charge and round up, then add one if you mow tall grass after rain or want a margin. Up to about a quarter acre, one 5 Ah or larger 56V or 60V battery is usually enough. Between a quarter and a half acre, plan on a 7.5 Ah or 10 Ah pack or two smaller batteries: the EGO POWER+ LM2135SP 21 in. Select Cut Self-Propelled Mower Kit ships with a 7.5 Ah battery and the Greenworks 80V 21 in. Self-Propelled Mower Kit is rated up to half an acre on its included 4 Ah pack. Past half an acre, a battery walk-behind becomes a two-battery job, and a battery rider such as the EGO POWER+ Z6 ZT4204L 42 in. Electric Zero Turn Mower or a gas mower starts to make more sense. Many mowers, including the EGO POWER+ LM2206SP 22 in. Aluminum Deck Self-Propelled Mower Kit, hold two batteries and switch automatically. See the best battery lawn mowers.

Should I stay on one battery platform?

Yes, for most homeowners. Batteries are the expensive part of a cordless yard, often a third or more of a kit price, and one platform lets the same packs run the mower, trimmer, blower and hedge trimmer. EGO's 56V system covers the widest range of big outdoor tools, Greenworks' 60V and 80V lines are strong on value, and Ryobi's 40V range is broad at lower prices. Mixing brands means buying and charging two sets of batteries. The platforms are compared in cordless outdoor tool systems and EGO vs Greenworks mowers.

Frequently asked questions

How long does a 56V 5Ah battery last on a mower?

A 56V 5 Ah battery holds 280 watt-hours. On a 21 inch self-propelled mower in normal grass that is roughly 14,000 square feet, about a third of an acre, or around 45 minutes of cutting. Tall or wet grass can cut that by a third. Push mode without self-propel stretches runtime, while high-lift bagging blades shorten it.

Can a battery mower handle a half acre?

Yes, with enough battery. A half acre is 21,780 square feet, which takes roughly 440 watt-hours in normal grass, about one 56V 7.5 Ah or 10 Ah battery, or two smaller packs. Several mowers are rated for half an acre on their included battery. In thick spring growth or tall grass, expect to need a second battery or a recharge partway through.

Do higher volt mowers run longer?

Not necessarily. Runtime depends on watt-hours, which is volts multiplied by amp hours. An 80V 2 Ah battery holds 160 watt-hours, the same energy as a 40V 4 Ah battery, so they cut similar areas. Higher voltage systems can deliver more power to the blade in thick grass, but for runtime always compare watt-hours rather than the voltage on the label.

How long does it take to charge a lawn mower battery?

Charge times vary widely by battery size and charger. Standard chargers commonly take one to several hours for a 5 to 10 Ah pack, while rapid chargers can cut that substantially. Check the charge time in the listing or manual for your exact battery and charger combination, and let a hot battery cool before charging, since most chargers pause charging until it does.

How long do battery mower batteries last before replacement?

Lithium-ion mower batteries typically last several years of normal use, with warranties commonly ranging from two to five years depending on brand. Capacity fades gradually with charge cycles and heat. Storing batteries partly charged in a cool place over winter, avoiding charging them hot and not leaving them fully drained all extend their useful life.

Researched, not professional advice. This page is compiled from published specifications, manuals, labels and owner-review consensus, not hands-on testing. Follow the manufacturer's instructions and product label, and consult a qualified professional where safety, chemicals, fuel or structures are involved. As an Amazon Associate we earn from qualifying purchases.