Battery Platforms
Watt-hours explained: the one number that compares any two battery tools
Voltage sells the tool. Amp-hours sell the battery. Watt-hours are the only figure that tells you how much work you actually bought.
Affiliate disclosure: we earn a commission if you buy through our links, at no extra cost to you. It never changes which product we rank first — here is how we're funded.
We have not tested these units. Every spec on this page comes from the manufacturer's own documentation and is linked to it. Every computed figure is arithmetic you can redo. Prices are checked daily — last verified January 1, 1970. Here is exactly how we pick.
Every cordless yard tool is sold on two numbers that cannot be compared across brands, and one number that can. Volts and amp-hours are the two. Watt-hours are the one. This page converts every pack we hold specs for, shows the arithmetic, and explains the 11% the sticker quietly borrows.
The formula, and why it is the whole game
Retail listings almost never do this multiplication for you, and there is a reason. "80V" on a shelf tag beats "40V" with any shopper who has not run the numbers, even when the 40V pack holds more energy. Do the multiplication and the marketing stops working, which is exactly what you want it to do.
Every pack in our registry, converted
| Tool | Pack as sold | Watt-hours | Working |
|---|---|---|---|
| EGO LM2135SP mower | 56V 7.5Ah | 420Wh | 56 x 7.5 |
| Ryobi RY40HPLM01B mower kit | 2 x 40V 6.0Ah | 480Wh owned, 240Wh live | 40 x 6.0, twice |
| Greenworks LM2108S mower | 80V 4.0Ah | 320Wh | 80 x 4.0 |
| Greenworks LM2054 mower | 40V 4.0Ah | 160Wh | 40 x 4.0 |
| Toro 21356 mower | 60V Max 6.0Ah | 324Wh (Toro's own figure) | Published, not computed |
| Kobalt dual-bay mower | 2 x 80V 4.0Ah | 640Wh installed | 80 x 4.0, twice |
| EGO LB6504 blower | 56V 5.0Ah | 280Wh | 56 x 5.0 |
| Ryobi RY404100 blower kit | 2 x 40V 4.0Ah | 320Wh | 40 x 4.0, twice |
| Greenworks 80V blower | 80V 2.5Ah | 200Wh | 80 x 2.5 |
| EGO LB6000 backpack | 56V 7.5Ah | 420Wh | 56 x 7.5 |
| EGO ST1521S trimmer | 56V 2.5Ah | 140Wh | 56 x 2.5 |
| Ryobi RY402110 trimmer | 40V 6.0Ah | 240Wh | 40 x 6.0 |
| Greenworks ST80L210 trimmer | 80V 2.0Ah | 160Wh | 80 x 2.0 |
| EGO CS1804 chainsaw | 56V 5.0Ah | 280Wh | 56 x 5.0 |
| EGO Z6 zero turn | 4 x 56V 10.0Ah | 2,240Wh installed | 56 x 10.0, four times |
Pack specifications transcribed from each manufacturer's published product page, checked 3 September 2026. Every watt-hour figure except Toro's is our arithmetic on the brand's own advertised voltage.
Read that table top to bottom and the platform argument makes itself. A 160Wh Greenworks 40V mower pack and a 2,240Wh EGO zero turn are separated by a factor of fourteen, and both are sold as "a battery".
The 11% the sticker borrows
One manufacturer in our registry publishes a real watt-hour figure rather than leaving you to multiply, and the number it publishes exposes something the others do not.
This is why we say "nameplate watt-hours" and show the working every single time. Compare within a convention, never across one.
Turning watt-hours into minutes
A pack size on its own still does not tell you whether the job gets finished. Divide the pack by the published runtime and you get watt-hours per minute, which is the figure that actually sizes a purchase.
| Tool | Energy | Published runtime | Watt-hours per minute |
|---|---|---|---|
| Greenworks LM2054 push mower | 160Wh | 40 min | 4.0 |
| Ryobi mower (per pack) | 240Wh | 40 min | 6.0 |
| EGO LM2135SP mower | 420Wh | 60 min | 7.0 |
| Toro 21356 mower | 324Wh | 45 min | 7.2 |
| Greenworks LM2108S mower | 320Wh | 33 min | 9.7 |
| EGO ST1521S trimmer | 140Wh | 30 min | 4.7 |
| Ryobi RY402110 trimmer | 240Wh | 67 min | 3.6 |
| EGO EA0800 edger (7.5Ah) | 420Wh | 100 min | 4.2 |
| EGO LB7650 blower, low | 280Wh | 150 min | 1.9 |
| EGO LB7650 blower, turbo | 280Wh | 15 min | 18.7 |
Runtime claims are each manufacturer's own. The per-minute column is our division of one published figure by another, shown so you can redo it.
Two things jump out. A blower on turbo burns roughly ten times what the same blower burns on low — 18.7Wh a minute against 1.9. And mowers vary by a factor of 2.4 between the most and least frugal, with the frugal one being the 20 inch push mower that has no drive motor. Efficiency in this category is mostly an absence of features.
#ad Check the Greenworks 40V 20" Push LM2054 price on Amazon — how we're funded.
Sizing a pack for your actual job
- Time the job once. Not the lawn area — the minutes. You already know roughly how long you spend mowing.
- Find the tool's watt-hours per minute from the table above, or divide its pack watt-hours by its published runtime.
- Multiply. 45 minutes on an EGO LM2135SP at 7.0Wh a minute is 315Wh.
- Add a third. Published runtimes are best case and packs lose capacity with age. 315Wh becomes about 420Wh — which is exactly the pack EGO ships with that mower, and not a coincidence.
#ad Check the EGO Power+ 21" Select Cut LM2135SP price on Amazon — how we're funded.
What this arithmetic cannot tell you
Watt-hours are a capacity figure, not a performance one. They do not tell you how a tool behaves at 20% charge, how much capacity a pack loses in year three, how cold weather changes the discharge curve, or how much of the rated capacity the electronics hold in reserve. Manufacturers publish none of that, and neither will we.
What watt-hours do give you is the only cross-brand comparison available in this category, and it is available to anyone with a calculator. Multiply before you buy.
The products discussed
Specs are the manufacturer's own and linked to the page they came from. Prices come from a live daily check; where we have no verified price we say so rather than print a stale one.
Toro 60V Max 21" Recycler Self-Propel (21356)
Toro · Toro 60V Max Flex-Force · Our score 8.3/10
#ad No verified live price right now, so we show none rather than a stale one. How we're funded.
The only manufacturer here that publishes the actual watt-hour figure for its pack -- and the number tells you something the others hide.
Published specs
| Model | 21356 |
|---|---|
| Deck | 21 in, 14-gauge steel |
| Battery | 60V Max L324, 6.0Ah, 324Wh |
| Charge time | 150 min |
| Runtime claim | Up to 45 min on the 6.0Ah |
| Drive | Personal Pace variable-speed RWD |
| Weight | 66 lb |
| Storage | SmartStow vertical |
Source: 60V Max 21 in. Recycler Self-Propel Lawn Mower (21356T), toro.com
Toro labels the pack 60V Max 6.0Ah and publishes 324Wh. 324 / 6.0 = 54V -- the nominal voltage, not the 60V max-charge figure on the sticker. Every brand's 'max volts' is roughly 11% above nominal, so a nameplate watt-hour number is always about 11% optimistic. This is the single most useful spec on this page.
What the numbers favor
- Publishes a real watt-hour figure (324Wh) instead of leaving you to multiply the marketing voltage
- 45 minutes from 324Wh, against Greenworks' 33 minutes from a nameplate 320Wh
- 14-gauge steel deck, the only steel deck spec published on this page
- SmartStow vertical storage -- a genuine constraint solver in a one-car garage
What they don't
- 150-minute recharge is the slowest here by a wide margin
- Toro's 60V line is narrower than EGO's or Ryobi's, so the platform grows less far
you are buying into a platform rather than a mower. Toro builds excellent mowers; the 60V Flex-Force tool range is not the one to bet a decade of yard tools on.
How it scores
Scores are our editorial weighting of the published specs above, not a test result. They are deliberately kept out of this page's structured data.
Greenworks 40V 20" Push LM2054
Greenworks · Greenworks 40V · Our score 8.0/10
#ad No verified live price right now, so we show none rather than a stale one. How we're funded.
40 minutes on a 160Wh pack and 57.5 lb to push -- the honest answer for a third of an acre and nothing more.
Published specs
| Model / SKU | LM2054 / 2549902 |
|---|---|
| Deck | 20 in |
| Max blade speed | 3200 RPM |
| Battery included | 40V 4.0Ah |
| Cut height | 1.2-3.6 in, 7 positions |
| Runtime claim | Up to 40 min |
| Weight | 57.5 lb |
| Rated for | Up to 1/3 acre |
| Warranty | 3-yr tool / 3-yr battery |
Source: 40V 20" 4-in-1 Push Lawn Mower (LM2054), greenworkstools.com
40V x 4.0Ah = 160Wh. Note it claims 40 minutes on 160Wh where the 80V flagship claims 33 minutes on 320Wh -- a 20 in deck and no self-propel drive motor is why.
What the numbers favor
- Lightest published weight on this page at 57.5 lb, and the only sub-60 lb mower here
- Claims 40 minutes from 160Wh -- the best published minutes-per-watt-hour of any mower on this page
- Same 3200 RPM blade speed as the 80V flagship
- 4-in-1 deck at the entry price
What they don't
- Push only -- no drive assist on any slope
- 1.2 in minimum cut height is lower than most cool-season lawns should ever be cut
- 120-minute recharge, three times the 80V model's 40 minutes
your lawn is over a third of an acre or has any real slope. Greenworks rates it to 1/3 acre and you will be pushing all 57.5 lb of it up the hill yourself.
How it scores
Scores are our editorial weighting of the published specs above, not a test result. They are deliberately kept out of this page's structured data.
EGO Power+ 21" Select Cut LM2135SP
EGO · EGO 56V ARC Lithium · Our score 9.1/10
#ad No verified live price right now, so we show none rather than a stale one. How we're funded.
The most watt-hours in the box of any flagship walk-behind here, on the platform with the widest tool range to grow into.
Published specs
| Deck | 21 in |
|---|---|
| Cutting torque | Up to 7.0 ft-lbs |
| Battery included | 56V 7.5Ah |
| Cut height | 1-4 in, 8 positions |
| Self-propel speed | 0.9-3.1 MPH |
| Runtime claim | Up to 60 min |
| Warranty | 5-yr tool / 3-yr battery |
Source: EGO POWER+ 21" Select Cut System (LM2135SP), egopowerplus.com
56V x 7.5Ah = 420Wh, using EGO's advertised pack voltage.
What the numbers favor
- 420Wh in the box -- the largest included pack of any flagship walk-behind on this page
- Eight cut-height positions from 1 to 4 in, the widest published range here
- Three interchangeable lower blades (mulching, high-lift bagging, extended runtime)
- 5-year tool warranty, the longest published on this page
What they don't
- EGO publishes torque (7.0 ft-lbs), not motor wattage, so it cannot be compared directly against Greenworks' 1500W figure
- The 7.5Ah pack that earns the runtime claim is also the expensive one to replace
your yard is under a quarter acre. You would be paying for 420Wh of headroom you will never discharge, and a 20 in push mower cuts the same grass.
How it scores
Scores are our editorial weighting of the published specs above, not a test result. They are deliberately kept out of this page's structured data.
EGO Power+ 765 CFM Blower LB7650
EGO · EGO 56V ARC Lithium · Our score 8.9/10
#ad No verified live price right now, so we show none rather than a stale one. How we're funded.
765 CFM and 200 MPH, with the turbo/low split published honestly: 15 minutes flat out, 150 minutes on low.
Published specs
| Max air volume | 765 CFM |
|---|---|
| Variable range | 260-580 CFM |
| Max air speed | Up to 200 MPH |
| Runtime (turbo) | 15 min on 5.0Ah |
| Runtime (low) | 150 min on 5.0Ah |
| Weight | 4.6 lb without battery |
| Noise | 64 dB |
Source: POWER+ 765 CFM Blower (LB7650), egopowerplus.com
280Wh (56V x 5.0Ah) over the published 15-minute turbo runtime = about 18.7Wh per minute. On low, 280Wh over 150 minutes is about 1.9Wh/min -- turbo costs roughly 10x the energy per minute.
What the numbers favor
- Highest published CFM and MPH of any handheld here
- Publishes BOTH turbo and low runtimes, so the trade-off is visible instead of averaged away
- 4.6 lb bare -- the lightest published weight of the handhelds on this page
What they don't
- 15 minutes of turbo on a 5.0Ah pack is the real constraint, whatever the 90-minute average says
- Sold bare in most configurations; budget for a battery and charger
you are clearing a small lawn. You will run it at 260 CFM forever and never touch what you paid for.
How it scores
Scores are our editorial weighting of the published specs above, not a test result. They are deliberately kept out of this page's structured data.
Where to buy the tools on this page
Every link below is an Amazon affiliate link. We show no price we have not verified today, so where there is no live figure the link says "check price" and takes you to the listing to read it there.
Best published watt-hour honesty
Toro 60V Max 21" Recycler Self-Propel (21356)
Toro · Toro 60V Max Flex-Force
Best for small yards
Greenworks 40V 20" Push LM2054
Greenworks · Greenworks 40V
Best overall
EGO Power+ 21" Select Cut LM2135SP
EGO · EGO 56V ARC Lithium
Best for large yards
EGO Power+ 765 CFM Blower LB7650
EGO · EGO 56V ARC Lithium
#ad As an Amazon Associate we earn from qualifying purchases, at no extra cost to you. How we're funded.
Common questions
What is a watt-hour?
Is a higher voltage battery better?
Why does Toro publish 324Wh for a 60V 6.0Ah pack?
How do I work out what size battery I need?
Do two batteries give me double the runtime?
Are amp-hours comparable between brands?
Sources
- Toro 60V Max 21 in. Recycler Self-Propel Lawn Mower (21356T), toro.com
- EGO POWER+ 21" Select Cut System (LM2135SP), egopowerplus.com
- Greenworks 40V 20" 4-in-1 Push Lawn Mower (LM2054), greenworkstools.com
- EGO POWER+ 765 CFM Blower (LB7650), egopowerplus.com
- EGO 8" Edger Attachment for Multi-Head System (EA0800), egopowerplus.com
Read next
- Battery Platforms
Pick the system once and the next four tools are decided for you. Start here.
- 40V vs 80V: what the voltage on the sticker actually buys you
Volts x amp-hours = watt-hours. The one calculation that makes every battery spec comparable.
- How long do electric lawn mower batteries last?
Runtime per charge is arithmetic. Lifespan in years is mostly warranty terms and honest uncertainty.
- How many batteries do you actually need?
Lawn size to watt-hours to pack count, plus the sequential-versus-simultaneous distinction.
- How to read a yard tool spec sheet (and what its silences mean)
Which figures are comparable, which are marketing, and what a missing spec tells you.
- How long do yard tool batteries take to charge?
Every published charge time converted to watt-hours per minute, and the mow-wait-mow arithmetic.