DeWalt 21 in. Mulching Blade

I swapped my stock mower blade for DeWalt’s 21-inch mulching blade to see if an OEM replacement could sharpen up cut quality on a couple of small suburban lawns I maintain. It’s a simple component, but it has an outsized impact on how a battery mower performs. After several weeks rotating between mulching, bagging, and side discharge, I’ve got a good feel for where this blade excels and where it asks for a little finesse.

Fit and installation

The blade is a direct 21-inch replacement with an S‑shaped center hole that seats positively on DeWalt’s compatible spindles. I installed it on a DCMWSP244 and briefly on a DCMWP233; in both cases, the fit was exact—no slop, no fiddling to line things up. It ships as a single blade, so if you like to keep a sharpened spare, plan on buying a second.

Installation is straightforward:

• Remove the battery and safety key.
• Tip the mower back safely.
• Note blade orientation and discharge direction.
• Mount the blade and torque the bolt to your mower’s spec (check your manual).

Balance out of the box was excellent; I didn’t pick up any new vibration after installation.

Build and edge out of the box

The steel profile is typical OEM: not overly thick or heavy, which is intentional on battery-powered decks to keep inertia and amp draw in check. The edge arrives functional rather than razor-sharp. That’s normal for factory blades—an overly thin edge blunts quickly and is harder on motors. That said, I always run a quick hone with a mill file before first use. Ten minutes to crisp the edge and deburr makes a noticeable difference in cut quality, especially with cool-season grasses.

If you routinely encounter sticks, gravel, or hidden roots, this is not a “brush blade.” It will nick and can deform on hard impacts. The trade-off is lighter spin-up and better runtime compared to heavy-duty aftermarket blades.

Mulching performance

In weekly mowing on fescue and bluegrass, the blade’s mulching profile performed well. With the mulch plug in and the deck cleaned out, it produced fine clippings that settled into the canopy rather than sitting on top. The finish was clean at moderate cutting heights (2.5–3.25 inches) and a sensible walking pace.

Pushing the blade harder—damp grass, dense growth, or taking more than a third of the blade off—revealed its limits. Like many single-blade 21-inch decks, airflow can press tall, wispy grass flat rather than cutting it cleanly, leaving an occasional line of stragglers. Three adjustments mitigated that:

• Slow the ground speed a touch and keep the motor in its higher power mode.
• Raise the deck a notch for the first pass, then drop to your target height for a quick cleanup pass.
• Keep the blade sharp and the underside of the deck free of buildup.

With those tweaks, straggling was rare in the same lawns.

Bagging and side discharge

For bagging, this blade pulls a decent vacuum and packs the bag evenly when the deck is clean and the turf is dry. In heavy, lush spring growth, I still needed to raise the deck or accept a slower pace to avoid clogging. If bagging is your default and you’re mowing aggressively tall grass, a high-lift blade designed for your specific deck may move clippings more forcefully at the cost of runtime and noise. For general residential use, this blade’s bagging performance is solid.

Side discharge is tidy, producing a uniform windrow that spreads out after a second pass. It’s not a “blower” blade that throws clippings to the fence line, but it’s efficient enough to keep the chute clear in most conditions.

Cut quality and consistency

After a file tune-up, the cut is consistent and leaves a crisp edge on cool-season grasses. Where I saw imperfections, they correlated with either:

• Overgrown turf where I was trying to cut too low in one pass.
• Dullness after a few encounters with sandy soil along a paver edge.
• Damp morning mowing.

In each case, technique or maintenance made the difference. The blade won’t mask poor conditions, but it responds well when you set it up for success.

Runtime, noise, and feel

Because it’s not a heavy or aggressive high-lift design, the blade is kind to battery life. On the self-propelled 244, I noticed a small runtime improvement compared with a thicker aftermarket blade I keep around for fall leaf shredding. Noise is moderate, and the tone is smoother than some serrated patterns I’ve tried. Most importantly, balance is excellent—no new buzz through the handle and no rattles at full speed.

Durability and maintenance

This blade’s durability is reasonable for an OEM profile. It holds an edge for several mows on clean turf, then benefits from a quick touch-up. I hit a small buried stone and raised a visible burr near the tip; a few passes with a file cleaned it up, but that kind of impact will shorten any blade’s life. If you encounter regular debris, you’ll spend more time at the bench grinder—or you might consider keeping a spare blade so you can swap mid-season and sharpen at your convenience.

A few practical tips:

• Check and clean the deck underside every few mows; caked grass kills airflow.
• Touch up the edge every 8–10 mowing hours or after any noticeable impact.
• Keep the edge angle consistent and re-balance the blade after sharpening.
• Replace the blade if you see cracks, significant bending, or if sharpening has narrowed the width past spec.

Compatibility notes

This replacement is built for DeWalt’s 21-inch walk-behind lineup with the S‑shaped center mount. It clicked right onto the spindles on the DCMWP233 and DCMWSP244 I used. If your mower uses the S-pattern spindle (often associated with part numbers starting 742‑05642/742P05642), you’re in the right neighborhood. Always confirm your model number and blade length before ordering.

Where it shines—and where it doesn’t

What I liked:

• Direct, wobble-free fit on compatible DeWalt decks.
• Balanced and efficient, with good runtime on battery mowers.
• Respectable mulching and bagging in typical weekly mowing.
• Easy to sharpen and keep in service.

Where it asks more of the user:

• Out-of-box edge is serviceable, but a quick hone elevates performance.
• In very tall or damp grass, the deck can lay grass over; technique matters.
• Not a heavy-duty option if your lawn hides sticks, stones, or ruts.

Who should choose this blade

If you own a compatible DeWalt 21-inch mower and want a known-quantity replacement that preserves the mower’s intended balance, power draw, and airflow, this blade is a smart pick. If your routine is weekly mowing and you keep the deck clean, it will give you a clean finish with the flexibility to mulch, bag, or side discharge as needed.

If you frequently let the lawn get out of hand, or you demand a single-pass golf-green cut in dense, tall grass, you may be happier pairing your mower with a more aggressive high-lift or specialized mulching blade designed for your specific deck—or adjusting your mowing cadence and cut height.

Recommendation

I recommend this DeWalt 21-inch blade to owners of compatible DeWalt walk-behind mowers who want an OEM-fit replacement that balances cut quality, runtime, and simplicity. It’s not the most heavy-duty blade, and it rewards you for keeping it sharp and mowing smart, but within those bounds it delivers consistently clean results and preserves the battery-first design of the mower. If your yard conditions are rough or you routinely tackle overgrown, wet grass, consider keeping a second blade on hand and plan on a two-pass strategy—or look for a purpose-built high-lift alternative compatible with your deck.