Impact drivers can drive more screws at faster speeds than a cordless drill, and they are ideal for working with large fasteners or driving screws without a pilot hole. Though they look like drills, impact drivers are very different internally. While a cordless drill merely rotates, an impact driver combines rotation with a series of rapid, successive blows. This creates two to three times the torque of a cordless drill, allowing you to power through tough projects without straining your wrists or forearms.
While a cordless drill's chuck can be adjusted to hold a variety of bits, an impact driver has a fixed chuck that only holds hex-shanked bits. In the past, that limited impact drivers to just driving tasks, but manufacturers now offer drill bits, hole saws and other hex-shanked bits designed specifically for use with an impact driver. Using a fixed rather than an adjustable chuck also results in a more compact tool that can be used more easily in tight quarters.
However, an impact driver can't completely replace a cordless drill. For starters, impact drivers are noisier than cordless drills, so most can't be used without hearing protection. Most also lack a clutch, which means they are not a good match for delicate jobs where you don't want to drive a screw too deep or to inadvertently strip its head. But for heavy-duty fastening jobs -- like building a deck or laying a new subfloor -- mechanics, contractors and homeowners say an impact driver makes the job faster and easier. The best cordless impact drivers are compact for easy handling, have a battery with adequate run time, and have good trigger control.
No impact driver earns stronger recommendations from professional sources than the Milwaukee 2453-20 (Est. $120). Despite its compact size – just 6 inches long and 2.25 pounds -- this tool is capable of producing 1,200 inch-pounds of peak torque. In two separate comparison tests, this Milwaukee impact driver trounces the competition, driving 219 to 229 fasteners before its battery gives out -- roughly 50 more than its nearest competitor. Testers are also impressed with the Milwaukee's features, including a brushless, 2-speed motor and an easy-insert chuck that locks bits in place with a push. It's backed by an impressive 5-year warranty, with the lithium batteries covered for two years.
There aren't that many reviews for the Milwaukee 2453-20 on retail sites, but the ones we found are overwhelmingly positive; for example a 5 star rating at HomeDepot.com based on nearly 50 reviews. Owners consistently describe this impact driver as powerful, sturdy lightweight, and comfortable to use. They're also pleased with extras such as the battery life indicator, reversible belt clip, and built-in LED light. Aside from a solitary complaint about a tool that broke on its first day, most users don't have a bad word to say about this impact driver.
The Milwaukee's biggest drawback is its high price tag: around $120 for just the bare tool, or $170 when sold as a kit with two batteries and a charger -- the Milwaukee 2453-22 (Est. $170). For homeowners on a budget, the Craftsman 17428 (Est. $60) might be a better option. This 12-volt impact driver comes with a 1.3-Ah lithium-ion battery and a smart charger that can restore a charge in half an hour. It's about as light as the Milwaukee -- just 2.3 pounds with the battery but not nearly as powerful, with a maximum torque of only 810 pounds.
This Craftsman impact driver draws mixed feedback in professional tests. It's the worst overall in one independent review, with abysmal marks for speed and run time -- but even there, it gets excellent ratings for power and charging time. This, combined with its low price, comfortable handling, and responsive trigger, inspires Popular Mechanics to name it the Best Value impact driver. Owners at Sears.com agree, with 95 percent of the nearly 160 reviewers recommending this lightweight, powerful, and sturdy tool. There are some complaints about its short battery life, but most owners consider it a good value nonetheless.
For most household jobs, a 12-volt impact driver (like the ones profiled above) has more than enough power. However, for heavy-duty fastening jobs, it's worth considering a larger 18-volt tool, which can drive even more fasteners on a single charge. We found strong reviews for the Ryobi P236 (Est. $60), which is available only as a bare tool, with the battery and charger are sold separately. In two professional tests, this impact driver exhibits exceptional power and run time, partly because it's one of the few impact drivers on the market that can be used with a high-capacity 4-Ah battery. It also features a quick-load chuck, a built-in LED light, and a handy magnetic storage tray for screws and extra bits. On the downside, it's very noisy, and the battery can take up to an hour to fully recharge. You'll also need to budget extra for the battery and charger; options include the Ryobi P128 1.5 Ah battery and charger kit (Est. $50), the Ryobi P108 4 Ah battery (Est. $100), the stand-alone Ryobi P117 charger (Est. $40) and more.
Owner reviews for the Ryobi P236 are mostly positive. Users say it's powerful, lightweight, and ergonomic, with great battery life. They appreciate its features, with one exception: many users complain that the built-in work light doesn't switch on until the bit starts spinning, so you never get a chance to align your screw before you start driving it. We also saw a few complaints about durability, but overall, the majority of owners recommend this impact driver.