DeWalt 20V MAX Brushless Cordless 1/4 in. Impact Driver Kit

Why I reached for this driver

I picked up the DCF840 for a week of punch-list tasks—cabinet installs, tapcons into block, and a small deck repair—where I wanted a compact driver with real muscle. On paper, the combination of a brushless motor, 1,700 in-lb of torque, and a short 5.1-inch head length looked like the right balance for tight quarters and stubborn fasteners. After living with it on my belt for several days, it slotted into my kit as a dependable, no-nonsense impact driver that prioritizes core performance over extras.

Build and ergonomics

The DCF840 is compact and light. The bare tool weighs 1.95 lb, and even with the included 20V compact packs it remains comfortable for extended overhead use. The handle contour and rubber overmold suit a range of hand sizes, and the belt hook (reversible) is sturdy enough that I stopped thinking about it after the first hour—always a good sign.

That short 5.1-inch front-to-back length matters more than spec sheets suggest. It let me get between studs and behind sink basins to set screws where a longer driver would force awkward angles. The overall footprint (7.6 in tall, 2.2 in wide) makes it a natural fit for cabinetry, HVAC, and electrical work where clearance is at a premium.

Power and driving performance

Despite its size, this driver hits hard. The brushless motor delivers up to 1,700 in-lb with a top speed of 3,200 rpm and 4,200 impacts per minute. On site, that translated to:

• Driving 3-inch exterior screws into pressure-treated 2x without pilot holes, consistently and without stall.
• Running 1/4-inch concrete screws into pre-drilled holes in block with no drama.
• Seating structural screws into doubled-up headers; it slows as you’d expect near the end, but keeps pushing.

It’s not the absolute most powerful impact in DeWalt’s lineup, but in real work it never felt undergunned for residential carpentry and general MEP tasks. I also used it to crack loose a set of passenger-car lug nuts as a quick test. It managed the job, though I wouldn’t count on an impact driver for routine automotive work or re-torqueing—use a proper torque wrench for that. Still, the headroom was reassuring.

Control and trigger feel

There’s no multi-speed selector or specialized assist modes here—just a well-tuned variable-speed trigger. That sounds basic, but the trigger modulation is excellent. I could feather drywall screws to flush without breaking paper and ease cabinet hardware snug without snapping small fasteners. For delicate work, it demands a bit more attention than a driver with a dedicated “precision” mode, but the learning curve is short.

The 1/4-inch hex drive secures bits positively and swaps quickly. The anvil has the expected slight wobble of an impact, but bit retention was solid with both short and extended holders.

Work light and visibility

The integrated three-LED array around the chuck is bright and even, reducing shadows better than single-LED designs. Working under a sink and in a dim crawl space, I could locate pilot holes and see screw heads clearly. It’s a small quality-of-life feature that matters when you’re trying to hit a bracket hole at arm’s length.

Runtime, batteries, and charging

The kit includes two 20V lithium-ion batteries (1.5 Ah) and a charger. For intermittent tasks—cabinets, hardware, electrical boxes—one battery usually lasted through a couple of hours of stop-and-go use, while the second sat on the charger. Under continuous heavy driving (deck screws, ledger fasteners), I swapped batteries more frequently.

A 90-minute charge time on the included charger is on the slower side for compact packs. The two-battery setup offsets that for most users, but if you plan to drive thousands of screws in a day, consider adding a higher-capacity pack (4.0–5.0 Ah) or a faster charger. Larger packs change the balance slightly—more rear weight, less nose dip—but provide noticeably longer runtime and a steadier feel when driving larger fasteners.

Noise and vibration

Like all impact drivers, the DCF840 is noisy under load. The impact mechanism’s sharp chatter is normal for this class, and hearing protection is sensible if you’re running it for long stretches. Vibration is well controlled for a compact driver; I didn’t experience finger numbness even after extended use, and the handle dampening is effective.

Durability and service

Brushless motors generally mean fewer wear parts, and nothing about the DCF840’s construction raised concerns. The casing fit is tight, vents are placed to avoid direct debris ingress, and the tool shrugged off a couple of waist-high drops to plywood without missing a beat. The kit is UL listed and comes with a 3-year limited warranty. The soft bag won’t protect it from hard knocks like a hard case would, but it’s convenient for tossing the tool, batteries, and a small bit set into the truck.

What I miss

• Speed/mode options: Higher-end drivers add multi-speed selectors and assist modes (precision, self-tapping, etc.). If you often switch between delicate hardware and big structural fasteners, you’ll notice their absence here.
• Battery capacity: The included 1.5 Ah packs keep weight down, but they’re not “all-day” batteries. Two packs help, but heavy users will want to budget for a higher-capacity battery.
• No on-tool bit storage: Not a dealbreaker, but it’s handy, and I missed it.

None of these are flaws in execution; they’re trade-offs that keep the kit compact and cost-effective.

Where it shines

• Tight spaces and overhead work, thanks to the 5.1-inch length and light weight.
• General carpentry: decking, framing connectors, ledger screws (with appropriate pilot holes), and long structural screws.
• Trades work: electrical boxes, tapcons, HVAC brackets, and appliance installs.
• DIY and homeowner tasks where one tool needs to cover a wide range of fastening jobs without bulk.

What to pair it with

For a simple, efficient setup, I’d add:
- A magnetic bit holder and a selection of impact-rated driver bits.
- A 4.0–5.0 Ah battery for long driving sessions.
- A compact right-angle adapter for truly inaccessible screws.

These additions extend the DCF840’s versatility without compromising its compact advantages.

Final thoughts

The DCF840 focuses on the fundamentals: strong brushless performance, compact dimensions, reliable trigger control, and useful lighting. It doesn’t chase every feature, but what it does, it does well. Over a week of mixed tasks, it felt like a trustworthy daily driver—easy to carry, powerful enough to avoid stalls, and precise enough for finish hardware with a little finesse.

Recommendation: I recommend the DCF840 to DIYers, homeowners, and pros who want a compact, lightweight impact driver with serious power and no fluff. It’s a great primary driver for general work and an excellent secondary driver for trades already using more feature-rich flagships but wanting a lighter, shorter option. If you need multi-speed modes, advanced assist features, or all-day runtime from compact packs, look at higher-tier models or add a larger battery. For most users, though, this kit’s balance of size, performance, and value is right on target.