Frequently asked questions
The questions readers ask most, answered in a paragraph each with a link to the full working.
Short answers below. Every one of them has a longer page behind it with the arithmetic shown, because the point of this site is that you can check our work rather than take it on trust.
About the tools
Common questions
How do I work out how much battery my lawn needs?
Time one mow, then multiply the minutes by about 7.5 watt-hours for a 21-inch self-propelled deck (or 4.0 for a 20-inch push mower) and add 30% for wet or overgrown grass. A 40-minute lawn works out around 390 watt-hours, which rules out most single-pack kits.
What are watt-hours and why do you use them everywhere?
Watt-hours are volts multiplied by amp-hours, and they measure the energy stored in a battery. It is the only figure that makes packs comparable across brands: a 40V 6.0Ah pack holds 240Wh and an 80V 2.0Ah pack holds 160Wh, so the lower-voltage pack runs 50% longer.
Is 80V better than 40V?
For power delivery under sustained load, yes -- higher voltage moves the same power at lower current, which means less heat. For runtime, voltage tells you nothing on its own. The 40V mower in our roundup outlasts both single-pack 80V machines because it carries more watt-hours.
Are EGO batteries interchangeable?
Yes, within the 56V ARC Lithium line -- any EGO 56V pack fits any EGO 56V tool. Larger packs simply run longer. EGO is the simplest of the major platforms in this respect: one outdoor platform, one pack family.
Do EGO batteries work with Ryobi tools?
No. Different voltages, different terminals, different battery management electronics. Neither company makes an adapter and no cross-brand combination is supported by either warranty. The same applies to every other cross-brand pairing.
Are all Greenworks batteries the same?
No, and this is the most common mistake within a single brand. Greenworks runs 24V, 40V, 60V and 80V as four separate, non-interchangeable platforms. Buying 'a Greenworks' commits you to nothing until you check which voltage line the tool sits on.
How long do battery mower batteries last?
Per charge, roughly 30 to 80 minutes depending on watt-hours. In years, manufacturers warrant packs for three to four. Beyond the warranty term nobody in this category publishes a capacity-retention figure, so an honest answer stops there.
Are battery lawn mowers worth it?
For a lawn that takes under about an hour to cut, yes -- one pack covers it and you drop five maintenance categories. Above an hour it depends on whether you will buy a second battery, because a gas can costs a few dollars and a pack does not.
What size mower do I need?
A 20-inch deck up to about a third of an acre, a 21-inch up to half an acre, a 21-inch with two batteries up to an acre, and a 42-inch riding deck beyond that. The real threshold is walking time -- an acre with a 21-inch deck is roughly 110 minutes on foot.
Do I need a self-propelled mower?
If your lawn has real slope, or the mower weighs over about 70 lb, yes. On flat ground under a third of an acre with a lighter mower, no. Slope decides this, not lawn size.
Is CFM or MPH more important on a leaf blower?
CFM moves volume and MPH dislodges what is stuck. Dry leaves on open ground are a CFM job; wet leaves matted into turf are an MPH job. The genuinely useful spec is the published variable range, because that is where you will actually work.
Which cordless tools are quietest?
In blowers, Ryobi's Whisper Series publishes 57 dB against EGO's 64 dB. In mowers, nobody publishes a decibel figure at all -- we checked all six flagship machines on this site and found none.
How much should I spend on a lawn mower?
Enough to cover your lawn's watt-hour requirement on a platform you would keep, and no more. Work out the requirement first, then compare cost per watt-hour across the mowers that meet it.
What is the biggest hidden cost of going cordless?
Battery replacement. Packs are warranted three to four years and are the expensive component. Across ten years, roughly a third of the total cost of a cordless yard setup is batteries -- bought, spared and replaced.
Should I buy tool kits or bare tools?
A kit for your first tool on a platform, because you need the pack and charger. Bare for every tool after that. Buying four kits leaves you with four chargers you did not need, and it is the single largest avoidable cost in cordless yard equipment.
Longer versions: 40V vs 80V, battery compatibility, how long batteries last, what size mower, how much to spend and CFM vs MPH.
About this site
Common questions
Have you tested the products you recommend?
No. Units we claim to have tested: zero. We compile manufacturer-published specifications, compute what they mean, and check prices daily. Every claim on the site links to the document it came from.
Then how do you decide what to recommend?
By reading the specifications and doing the arithmetic, the way you would size any piece of equipment. Watt-hours, energy per minute, cost per watt-hour, cleaning units and passes-per-lawn are all computable from published figures, and we show every calculation.
Why do some of your tables say 'not published'?
Because the manufacturer did not publish that figure and we will not invent one. Three of six mower brands do not state the weight of their flagship machine. Leaving the cell empty is more useful than filling it with an estimate.
Why don't you show prices in your articles?
Because a price typed into a page in September is wrong by October. Prices come from a live daily check on the buy buttons, stamped with the date verified, and anything older than 48 hours disappears rather than misleading you.
How does this site make money?
Affiliate commission on qualifying purchases through our links, at no extra cost to you. We accept no free products, no sponsored placements and no payment for inclusion, and commission never decides a ranking.
I found an error. What should I do?
Tell us. Corrections are verified against the manufacturer's own documentation, then fixed along with every calculation downstream of the error, and material corrections are marked visibly on the page.
Longer versions: how we pick, editorial policy, affiliate disclosure and about us. Something not answered here? Ask us.