This website is reader-supported. When you buy through links on our site, we may earn an affiliate commission.

Sun Joe MJ420C Review

Sun Joe MJ420C

Check Price

sun joe mj420c

(Rated: 4.4 / 5) Review by Frank Lowery
Ease of Assembly11110
Balance And Handling11111
Cut Quality1110.50

A cordless electric lawn mower is the kind of tool that can make your life a lot easier for a number of reasons. Unlike a gas powered lawn mower, an electric model is never going to need regular tune ups, make you keep smelly gas cans in your garage, or produce lots of carbon emissions. And unlike a plug in electric lawn mower, you will not be limited in your range of mobility by the length of an extension cord. You can roam all over the yard with a battery powered lawn mower. But a cordless electric lawn mower is only as good as the battery that is driving it. If that battery does not have a long enough run time, you may find that you will have trouble finishing the entire lawn on a single charge. Fortunately, the Sun Joe MJ420C is a cordless electric lawn mower with a run time that is significantly longer than the industry average.

Review Summary

review summaryThe Sun Joe MJ420C is a battery powered lawn mower that has a run time of a full hour, placing it head and shoulders above what most other battery powered models can offer. This is the kind of performance that you need no matter what size your lawn is. If you have a medium sized lawn, the extra run time will ensure that you can definitely finish cutting the entire area without needing to recharge the battery. And no matter what size your lawn is, with a full hour to cut it you can take your time and be sure that you are leaving it looking its absolute best.

That is the kind of real convenience that you want from your cordless electric lawn mower, and it is exactly what you are going to get from the Sun Joe MJ420C. Along with a longer battery run time, you get an extended battery life as well, which means you will be using the Sun Joe MJ420C much longer than you would with an inferior model. And along with a number of other very convenient features, the battery run time ensures that you are getting the most convenient experience possible out of the Sun Joe MJ420C.


review specificationsThe Sun Joe MJ420C is a cordless electric lawn mower that weighs 40 pounds and has overall dimensions of about 48 x 22 x 35 inches. It has a 24 volt removable battery that takes sixteen hours to reach a full charge. It can hold that charge long enough to run the Sun Joe MJ420C for sixty minutes.

Dimensions48.4 x 22.2 x 35.4 inches
Power24V Removable Battery (Inc. 1 battery)
Charge Time16 Hours to 100%
Deck Size
(cutting swath)
Mulch/Bag/DischargeRear bag
Cutting Areaup to 1/4 acre
Runtime charge
(conditions may vary)
up to 60 minutes
Drive SystemManual Push
StarterPush button
Height AdjustmentOne point (4 positions)
Height Settings1- to 1-4/5-inch
Wheel Size8-inch rear
Weight40 pounds
Warranty2 years

The Sun Joe MJ420C has a cutting deck width of 16 inches, which allows it to cut up to ¼ of an acre of grass in just a single charge. It is a manual push drive system with an ergonomic handle and big, eight inch wheels. It has rear bag grass collection and four height adjustment options.


review descriptionYou may have shied away from buying a cordless electric lawn mower for a number of years because you had heard that they do not have the kind of extra long run times that you need in order to make sure your entire lawn got a clean, even cut. Well, with the Sun Joe MJ420C those days are over. This lawn mower has the kind of extra long run time – at a full hour – that will allow anyone to get the kind of high quality, professional grade cut for their lawn that for a long time simply was not possible to achieve with a cordless electric lawn mower.

The Sun Joe MJ420C is a surprisingly compact and light lawn mower too, especially when you consider the run time the battery provides. Most cordless lawn mowers are still fairly bulky, heavy machines, with batteries that add lots of extra weight to them and make them difficult to use. But the Sun Joe MJ420C is a different kind of cordless lawn mower. It not only has a more powerful battery but one that is also better designed, so that it can deliver lots of power in a compact and efficient size.

Those are not the only great features the Sun Joe MJ420C has to offer its user, however. You get a sleek, convenient design that is ergonomic and easier to use. The Sun Joe MJ420C has bigger wheels than other lawn mowers, which makes sure you get an even cut no matter what the terrain is. And the Sun Joe MJ420C has the kind of great price that makes it accessible to any homeowner out there – even those on a budget.


review prosThere are a lot of great features on the Sun Joe MJ420C that help to make it one of the better cordless lawn mowers on the market today. While it has the basic Pros that a lot of other cordless lawn mowers have to offer – such as limited carbon emissions, great features and ease of use – the Sun Joe MJ420C has one thing that a lot of similar models do not have. With a battery that has one of the longest run times you can find on one of these machines, the Sun Joe MJ420C is clearly a superior choice.

  1. Much better for the environment : With a cordless electric lawn mower, you are enjoying a number of benefits over a gas powered model. You will never have to deal with smelly gas cans in your garage or have to do the kind of maintenance that gas powered lawn mowers often need. And you will never produce a single carbon emission at the point of use. No more fumes in your yard – and your household carbon footprint will be lowered as well.
  2. Compact and lightweight : A lot of cordless electric lawn mowers are fairly heavy and bulky, which can make it rather difficult to move them around the yard or get into and out of the garage or tool shed. The Sun Joe MJ420C weighs just forty pounds, making it one of the most lightweight models you can find today. It weighs so little that you can practically pick it up, and it is so small that storing it will be easier than ever.
  3. Extra large wheels : The wheels on the Sun Joe MJ420C are a full eight inches tall – making them a lot bigger than what is offered on most lawn mowers out there, battery powered or otherwise. These big wheels will make it a lot easier to move the Sun Joe MJ420C over bumpy or uneven ground without losing the evenness of the cut. Big wheels will help hold the cutting deck of the Sun Joe MJ420C steady without too much effort on your part.
  4. One point height adjustment : The wheels on the Sun Joe MJ420C also have four height settings, so you can pick the best height level for the conditions on the ground. And best of all, the height adjustment can be easily completed in just seconds, because all it takes is a single lever at the rear of the lawn mower. That means you will always be able to get exactly the right height to keep your lawn looking its best.
  5. One hour run time : At a full 60 minutes, the Sun Joe MJ420C has a run time that is much longer than average for any cordless electric lawn mower on the market today. Most of us could probably cut our entire front and back lawns twice with that kind of run time, especially when you combine it with the fact that the Sun Joe MJ420C has a sixteen inch cutting width. One of the main drawbacks to cordless electric mowers – run time – is eliminated by the Sun Joe MJ420C.

I saved the best feature for last on that Pros list. With a run time of a full hour, the Sun Joe MJ420C really blows away a lot of the competition. It has everything you look for in a battery powered electric mower. You get all of the benefits of a gas powered or plug in lawn mower with the Sun Joe MJ420C, but none of the drawbacks traditionally associated with one of these machines.


review consThere are a few minor issues that the Sun Joe MJ420C presents, though. Of course, I do not think that any of these can take away much from the great Pros the Sun Joe MJ420C has to offer, particularly the extra long run time that can ensure you will be able to tackle the biggest lawn projects with it. But I think these Cons are worth covering all the same, just so you know exactly what the Sun Joe MJ420C has to offer its owner. Let’s take a look.

  1. Only one grass clippings option : Because of its unique design that is reminiscent of manual push reel lawn mowers, the Sun Joe MJ420C does not have the ability to support a mulching option, and side discharge is clearly out of the question. The good news is that the Sun Joe MJ420C has a rear bag that catches grass clippings for later disposal or composting. For most users this should be plenty, especially because it keeps grass clippings from clumping in the lawn.
  2. Sixteen hours to fully charge : Sixteen hours is a long time to wait for a full charge. It basically means that you will have to plug in your Sun Joe MJ420C the day before you want to use it, which can be a hassle if you accidentally forget to do so. The best way to avoid this is by charging the Sun Joe MJ420C as soon as you are finished using it. That way it will always be standing by and ready to start cutting your lawn.
  3. Limited range of height settings : While the Sun Joe MJ420C has four height settings, which is better than a lot of other lawn mowers out there, the range of those four settings is not that great. You only have a range of one to 1 4/5 inches. At less than an inch of wiggle room, you are going to have to pay pretty close attention to how fast your lawn is growing to make sure you can cut it while the Sun Joe MJ420C can still handle it.
  4. Struggles with weeds and tough grass : This is a problem that a lot of cordless and even plug in electric lawn mowers have to contend with, so while I do not think it is a major Con, it is still worth talking about. On varieties like Fescue and Bluegrass, the Sun Joe MJ420C should have no problems. But if you are cutting tougher Bermuda Grass with it, you may find that it will struggle. It may also have difficulty with thick, tough weeds, which it will often run right over without even hurting.
  5. May have trouble with taller grass : Because the Sun Joe MJ420C has a fairly small range of height options, you may have trouble if you try to cut taller grass with it. Any grass that is more than four or five inches tall will be fairly difficult for the Sun Joe MJ420C to get through. Not only that, but cutting grass less than 1/3 of its initial height can seriously damage it, so you should avoid letting your lawn get more than five and a half inches tall before you use the Sun Joe MJ420C to cut it.

I think that you will agree that for the most part, the Sun Joe MJ420C does not have any of the kind of serious issues that can take away from all of its great features – especially the extra long 60 minute run time. Overall the Cons the Sun Joe MJ420C presented were either fairly common for cordless and plug in electric lawn mowers, or else did not seriously affect its overall performance in any way. This remains a very solid lawn mower at a great price.

Product Comparison

review comparisonPros and Cons are one thing, but the best way to be fully informed about whether or not a particular lawn mower is the best one for you is by comparing it to similar models in its class. This way, you can get a good picture of what the market has to offer in terms of size and performance, and see how a lawn mower like the Sun Joe MJ420C stacks up to other ones like it. Let’s take a look.

 sun joe mj420cSun Joe
toro 20360Toro
black decker cm1836Black & Decker
Dimensions48.4 x 22.2 x 35.4 inches56.7 x 21.5 x 38.9 inches37.5 x 15.5 x 21.5 inches
Power24V Removable Battery
(Inc. 1 battery)
36V Removable Battery
(Inc. 1 battery)
36V Integrated Battery
(Inc. 1 battery)
Charge Time16 Hours to 100%15 Hours to 100%12 Hours to 100%
Deck Size (cutting swath)16-inch20-inch18-inch
Mulch/Bag/DischargeRear bagMulch and bagRear bag (mulching insert and side discharge chute sold separately)
Cutting Areaup to 1/4 acreup to 1/4 acreup to 1/3 acre
Runtime charge (conditions may vary)up to 60 minutesup to 45 minutesup to 45 minutes
Drive SystemManual PushManual PushManual Push
StarterPush buttonPush ButtonHandle pull
Height AdjustmentOne point (4 positions)Each wheel (8 positions)One point (single lever adjusts all four wheels simultaneously)
Height Settings1- to 1-4/5-inch1- to 4-inch1-1/2- to 3-1/2-inch
Wheel Size8-inch rear7-inch front / 8-inch rear7-inch front / 8-inch rear
Weight40 pounds77 pounds64 pounds
Warranty2 years2 years2 years

As you can see, the Sun Joe MJ420C has the longest battery charging time and the smallest deck size of the three lawn mowers, but in most other areas it is the superior one. It has the longest run time of the three, the largest wheel size, and it weighs the least. These three factors are going to mean it is easier to use, will give the most even cut of the three, and allow the user to cut the largest area with it.


review conclusionOnce you have compared a particular lawn mower like the Sun Joe MJ420C against similar models in its class and seen that it is the best one, it can be tempting to buy it right away. But before you do so, let’s take another look at the Pros and Cons lists just to be sure this is the right one for you.

Conclusion Pros

  1. Much better for the environment.
  2. Compact and lightweight.
  3. Extra large wheels.
  4. One point height adjustment.
  5. One hour run time.

The Sun Joe MJ420C has a lot of the basic Pros that superior cordless lawn mowers offer – a compact size and weight and convenient features like wheels and adjustments. But where it really shines is in its sixty minute long run time – which is much better than other cordless lawn mowers.

Conclusion Cons

  1. Only one grass clippings option.
  2. Sixteen hours to fully charge.
  3. Limited range of height settings.
  4. Struggles with weeds and tough grass.
  5. May have trouble with taller grass.

While a shorter run time would be more convenient, it does not really affect the performance level you are getting from the Sun Joe MJ420C, and the same can be said for most of the other Cons I could find on this model. Overall I think the Sun Joe MJ420C is still one of the best cordless lawn mowers out there.

Final Word

A cordless lawn mower is only going to prove to be convenient if it can get your entire lawn cut on the first use, without having to stop to swap out batteries or wait for it to charge back up again. On a lot of cordless models, this is a bit of a gamble – you might find yourself racing to finish the job before the battery runs out. But on the Sun Joe MJ420C, you can take your time and make sure you give the entire lawn a perfect cut. That is because the Sun Joe MJ420C has a run time that is a lot longer than what you can find on most other cordless lawn mowers. At a full hour, you can take care of even larger lawns at your own pace, without having to worry about running out of juice. That is the kind of convenience you want from a cordless lawn mower – and with the Sun Joe MJ420C you can finally have it.

Best Price

review pricesOnce of the best features the Sun Joe MJ420C has to offer is not even part of the lawn mower – it is on the price tag. The Sun Joe MJ420C has a surprisingly competitive price, especially when you consider the fact that it offers a battery with a superior run time to just about anything else that is on the market today. With the kind of exceptional performance the Sun Joe MJ420C has to offer, you might expect it to be priced well above average for cordless lawn mowers, but in fact it has a price that is comparable with some of the most affordable models out there.

Sun Joe MJ420C

Check Price

Click the button to get the best deal for Sun Joe MJ420CCheck Price
Click this link to enjoy Exclusive SEPTEMBER 2023 Deals »