Kobalt 40V Mower Review – 40V Max Self-Propelled

PTR Review
  • Pro Review 8.5

The Kobalt 40V mower's 8th-place finish is a bit of an unflattering result. The truth is that, especially for the money, this is a great little mower. Granted, you'll either have to have a smaller lot or a second battery if you want this mower to run for over a half an hour. But, for the right homeowner, Kobalt has made a great lawn tool here.

Overall Score 8.5 (out of 10)

Kobalt’s Smaller Model Presents a High-Value Option For Smaller Lawns

Our recent best lawn mower review showed us a lot of what the market has to offer for both push and self-propelled mower options. Kobalt offered two battery-powered models for our competition. The 80V model, with its super run time, power, and low sound levels, wound up winning the whole thing for the cordless self-propelled category. The Kobalt 40V cordless mower performed similarly, but we found it to be a  scaled-down version of our winner, targetting homeowners with a smaller-sized lawn.


  • Extremely quiet at 79 dB(A)
  • Excellent value at $379
  • Steel deck
  • Easy vertical storage


  • No battery level indicator on mower
  • Short runtime owing to the smaller battery

Editor’s Note: Check out our best battery-powered mower article for our top picks.


Cutting Power

Cutting speed is important because the faster the blade spins, the easier time your mower has cutting the grass. As the grass gets thicker, the harder the mower has to work at keeping that blade tip speed up.

In the case of battery-powered mowers, as the mower senses more resistance the brushless motor directs more power to the blade tip. So we took a look at the blade tip speeds of all our cordless mowers – under both light and heavy loads – to see which model fared the best in the cordless class.

Kobalt 40V Cordless Mower Review - Self-Propelled 40V Max

Simulating a normal weekly maintenance cut, we tested the Kobalt 40V mower under a light load. Its 19-1/4″ blade whipped around at 2780 RPM, which pans out to 159.1 MPH blade tip speed. Certainly, this is fast enough to get through a maintenance cut easily enough, but it was one of the slower models we tested.

However, when we threw the Kobalt 40V self-propelled mower under a heavier workload, we saw the blade tip speed accelerate 22.6 MPH higher. As the mower felt more resistance, it ramped up the power to 3174 RPM, or 181.7 MPH blade tip speed for a mid-pack finish.

If we pull out just the 40V class (36V/40V Max), only Stihl brings more blade speed to the table when things get tough. That’s pretty good company to keep.

Kobalt’s cutting power is pretty standard for cordless mowers. It handles your weekly cut well and has the power to push through a couple of extra days worth of growth. If you let your lawn go much longer, you need to cut higher and work your way down or cut partial swaths to get it back under control.

Cutting Area

While all of that power might is welcome, if it costs you in a big way with your runtime, is it worth it? It really depends on the size of your lawn. In this particular case, you’re looking at being able to mow right around 1/4 acre on one charge of the kitted 40V battery.

Kobalt 40V Cordless Mower Review - Self-Propelled 40V Max

We got 32 minutes of runtime under a maintenance load. That time will drop considerably if you’re working with an overgrown lawn. With the drive set at 2.5 MPH, that’s 11,293 square feet of cutting or 0.26 acres. Using just the battery in the kit a 1/4-acre or smaller lawn is a good fit.

Of course, you can always buy additional batteries to get more runtime.

Noise Level

Kobalt seems to excel at making a quiet mower. Both models the brand entered into our shootout fared really well from a sound level standpoint.

Kobalt 40V Cordless Mower Review - Self-Propelled 40V Max

The benefits of having a quiet mower are plenty. The less sound pumping from your mower, the less you need to worry about damaging your hearing. That’s why the 79 dB(A) coming from the Kobalt 40V cordless mower is so nice. 79 dB(A) is quiet enough that you don’t really even need ear protection according to OSHA standards.

Keep in mind that’s a no-load test to see how much noise the mower makes on its own. Actual cutting, particularly when the motor calls on additional speed, will create a little more noise.

What’s even better, with mowers running at this sound pressure level, you can likely run your mower early in the morning or later at night without disturbing your neighbors. I wish that my neighbor – who believes that 6:45 on a Saturday morning is an appropriate time to start mowing – would hop on the cordless train.

Feature Set

Adjustable Self-Propelled Drive

Rather than using a pressure-sensitive throttle, the Kobalt 40V mower opts for an adjustable lever throttle. The result is an easy-to-use, set-it-and-forget approach to self-propelled drives. Mostly, we’re just happy when a mower will do the hard work of pushing itself, but it’s nice when the system works like it does here.

Kobalt 40V Cordless Mower Review - Self-Propelled 40V Max

Some mowers are beginning to experiment with on-the-go or even self-adjusting pacing. The better designs we’re seeing are on gas mowers and Kobalt’s traditional approach is just fine with us.

Steel Deck

While some manufacturers that opt for plastic decks, Kobalt uses a traditional steel deck with the 40V model. As Floridians with a load of sugar sand to deal with, steel is our preference since it tends to hold up to wear and tear better.

Kobalt 40V Cordless Mower Review - Self-Propelled 40V Max

Height Adjustment and Range

A single-point cutting height adjustment means that we only have to bend over once, rather than 4 times to adjust all four wheels. There are pros and cons to a single-point design. In general, Kobalt’s steel deck keep the frame rigid and we’re happy to have the convenience. Some mowers get loosey-goosey with a single-point system.

Kobalt 40V Cordless Mower Review - Self-Propelled 40V Max

Speaking of making adjustments to the cutting height, the Kobalt 40V mower gives you seven options ranging from 1.25″ – 4.375″. That a pretty wide range that should cover just about any grass species you have.

Handle Positions

We all come in different shapes and sizes, so we appreciate when a mower lets us customize the handle position to accommodate various heights. The Kobalt 40V mower gives us 3 working positions to choose from, as well as an easy folding handle that makes vertical storage a snap.

Discharge Options

Whatever your preference for how you want to handle your clippings is, the Kobalt 40V mower has you covered with mulching, bagging, or side discharge.

Kobalt 40V Cordless Mower Review - Self-Propelled 40V Max

Missing Features

  • No battery charge light indicator on the mower


The Kobalt 40V self-propelled mower shines when it comes to value—it came in 2nd for value in its class. The only mower that presented better value (and the margin was extremely slim) was the Greenworks 60V mower.

It retails for $379 from your local Lowe’s or online, and it comes with a 40V 5.0Ah battery and charger.

Of course, we look at other factors besides price when considering a value score. Build quality and warranties factor in heavily too. We liked the overall build quality of this Kobalt model, and the 5-year warranty that comes with this mower gives us the assurance that Kobalt thinks that they’ve put together a pretty solid mower as well.

Plus, the Kobalt 40V lineup includes this mower, a chainsaw, a blower, a string trimmer, a hedge trimmer, a polesaw, and a snowblower. Should you decide to invest in the brand’s 40V line of OPE tools, this mower provides a budget-friendly inroad.

The Bottom Line

The self-propelled version of the Kobalt 40V mower does a fine job for homeowners that keep up with their lawns. It doesn’t have the cutting power and runtime that some of the higher voltages do. But it makes up for it with quiet operation and fantastic pricing for bargain hunters.

Pick this one up if your lawn is a 1/4-acre or less and you rarely let it go more than a week between cuts during the peak growing season.

Kobalt 40V Mower Manufacturer Specs

  • Model Number: KMP 5040-06
  • Cutting Swath: 19.5″
  • Deck Type: Steel
  • Deck Adjustment: Single-lever
  • Cut Height Adjustment: 7-Position
  • Cut Height Range: 1.38″ – 3.75″
  • Bagger Included: Yes
  • Brushless Motor: Yes
  • Battery Amp Hours: 5 Ah
  • Charge Time: 2.5 hours
  • Cutting Range: 1/4 acre to 1/2 acre
  • Drive Type: Rear wheel drive
  • Assembled Weight: 65 lbs
  • Discharge Locations: Side and rear
  • Warranty: 5-year limited
  • Price: $299 at Lowe’s

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