DeWalt 21 in. 150cc rear-wheel drive self-propelled lawn mower

Why I picked this mower and where I used it

I put the DeWalt 21-inch self-propelled mower to work on two properties: a modest, mostly flat suburban lawn with a mix of fescue and bluegrass, and a sloped, rougher turf area that routinely grows past 6 inches between cuts. I wanted to see how a 150cc Briggs & Stratton, rear‑wheel‑drive package with a steel deck would handle both easy weekly maintenance and tougher, overgrown sections. On paper, it’s a straightforward proposition: a 21-inch steel deck, ReadyStart pull cord, 2-in-1 cutting (mulch and bag) with a variable-speed single lever for traction control, and six height positions from 1.25 to 3.75 inches. Mine arrived with a 2.3-bushel rear bag, a mulch plug, and a bolt-on side discharge chute.

Setup and first impressions

Out of the box, setup was simple: unfold and secure the handle, add the provided engine oil, fuel up, and go. The ReadyStart system lived up to its name—cold or warm, the engine fired on the first pull every time in my testing. The 15-gauge steel deck feels stout, and the overall construction looks clean at first glance. However, I immediately noticed two things:

• The drive-speed lever’s travel is short, and the engagement point is abrupt. Fine speed control takes practice.
• The bagger chute door is retained by a simple metal rod through plastic ears. It works, but the retention isn’t confidence-inspiring.

Engine, noise, and fuel use

The 150cc Briggs & Stratton 625EX-series engine is the best part of this mower. It starts easily, idles smoothly, and has enough grunt to keep the blade spinning in thick grass without bogging. It’s a typical gas-mower noise profile—loud enough that hearing protection is a good idea—but not unusually shrill or rattly for its class.

Fuel economy is decent. With a 0.25-gallon tank, I saw about 35–45 minutes per fill depending on grass height and how hard I leaned on the self-propelled drive. Plan on topping up for larger yards.

Drive and handling on flat and sloped turf

Rear-wheel drive is the right call for traction, and this mower climbs well. On my slope, it tracked straight and didn’t spin out, even with damp grass. The downside is the speed control. The single-lever drive engages quickly and can lurch forward when you first squeeze in—especially if you’re used to mowers with a more progressive engagement. That tendency makes the front end feel light. If you goose the lever, the nose will pop up a bit, which can lead to uneven cuts at the beginning of a pass or when you pivot.

Once you find the sweet spot on the lever and resist the urge to over-squeeze, the mower settles into a steady pace. For tight maneuvering, it’s easy enough to feather the drive or release it and push manually. Wheel size is 8 inches all around; that keeps the mower compact, but it’s not as forgiving as a high-wheel design on rough ground.

Actionable tip: Use a gentle squeeze to bring the drive in, and drop the front wheels one notch lower than the rears if you notice nose lift or washboarding on bumpy lawns.

Cut quality and deck performance

Cut quality is good—but not great—when the blade is sharp and the grass is at a reasonable height. On my weekly-maintained lawn at 2.75–3.25 inches, the mower left a clean, even finish with minimal stragglers. On fast-growing sections and taller grass (5–7 inches), I needed to slow my walking pace and occasionally double-cut to get the crisp look I expect. The 1.25–3.75 inch height range works for most yards, but if you prefer a true 4-inch summer cut, you’re out of headroom.

Mulching performance is solid in moderate growth. In lush or damp grass, the deck loads up and the underside cakes quickly, which hurts airflow and cut consistency. Bagging cleans up the stragglers better than mulching on long or wet turf, but I did see some chaff blowback around the rear opening when the bag wasn’t seated absolutely perfectly.

Actionable tip: Keep the blade sharp, spray the deck underside with silicone or a dry Teflon spray to minimize buildup, and slow the drive in heavy or wet grass. If you need to recover from overgrowth, use the side discharge chute or bag instead of mulching, then return to mulch mode for maintenance cuts.

Bagging, side discharge, and usability quirks

The 2.3-bushel bag holds a useful amount of clippings and attaches easily. Dumping clippings into tall paper lawn bags is awkward, though—the bag’s frame and opening angle don’t line up naturally with a bag rim, so you may find yourself juggling. The included side discharge chute works for clearing heavy growth, but it’s a bolt-on piece that adds a couple of minutes to swap modes.

The bigger issue I ran into is the rear flap/door and its retaining rod. After several mows, the rod began to migrate laterally, which can let the flap walk out of its pivot. It never fully released on me, but it moved enough to warrant a fix. Adding small E-clips or axle caps to the ends of the rod solved it permanently. It’s a simple, inexpensive upgrade—but it’s also something I’d prefer not to do on a new mower.

Actionable tip: Inspect the flap rod after the first few uses. If it’s drifting, add clips or use a slightly longer rod with locking caps. Also make sure the bag is fully seated; a loose fit is the fastest way to get clippings in your face.

Ergonomics and vibration

The handle geometry is comfortable overall, but vibration through the bar is noticeable at full song. After a long session, my hands appreciated padded gloves. The operator presence bar sits fairly close to the main handle; depending on your grip, the two bars can pinch the base of your thumbs. Slightly repositioning my hands and wearing gloves prevented hot spots, but this is one area where a bit more clearance or a softer overmold would help.

Actionable tip: Wear lightweight anti-vibration gloves and adjust your grip so the presence bar isn’t resting on your thumb knuckles. If you share the mower with different-height users, experiment with handle angle to keep wrists neutral.

Maintenance and durability notes

• Blade: Mine arrived acceptably sharp, but a quick touch-up improved cut quality.
• Fasteners: After a handful of mows, I found two drive cover screws slightly loose. A routine once-over with a screwdriver kept everything snug.
• Deck: The 15-gauge steel deck is sturdy and shrugs off the occasional stick or hidden pine cone.
• Engine: Zero starting drama. Change the oil as scheduled and you should be fine.

I did not experience any self-propelled failure during my test window, but the abrupt engagement and the loose screws I encountered suggest you should make a habit of checking the drive hardware for the first few outings.

Who it suits—and who should look elsewhere

This mower makes sense if:
- You need rear-wheel traction for hills and want reliable, easy starts.
- You mostly mow weekly and can slow down for the tall/wet patches.
- You don’t mind minor tinkering (tightening screws, adding clips to the flap rod).

You may want to pass if:
- You demand a truly smooth, progressive drive control out of the box.
- You need a higher max cut than 3.75 inches for summer heat stress.
- You’re sensitive to handle vibration or don’t want to wear gloves.
- You want a bagger that dumps cleanly into paper lawn bags without fuss.

Recommendation

I can’t give the DeWalt 21-inch self-propelled mower a blanket recommendation. The core—engine, traction, and deck durability—is solid, and it starts reliably. But the user experience is held back by an abrupt drive engagement, noticeable vibration, a finicky bag interface, and a flap-rod retention design that really should be stronger from the factory. If you prioritize hill-climbing traction and hassle-free starting, and you’re comfortable doing small fixes and adopting a gentler drive technique, it can serve you well. If you want refined controls, better ergonomics, and zero tinkering, there are smoother options in this price range.