These power tools get the job done, wherever it needs doing.
By Tony Carrick and Bradley Ford Updated: Jun 13, 2024 11:25 AM EDT Jump to Products Save Article
Gear-obsessed editors choose every product we review. We may earn commission if you buy from a link. Why Trust Us?
Historically, impact wrenches were predominantly pneumatic, or air powered, which left them squarely in the domain of professional mechanics. To run a typical 1⁄2-inch pneumatic impact wrench, an air compressor putting out close to 100 psi is typically required—and that’s a significant investment.
The good news is that battery-powered impact wrenches have gotten better as battery technology improves, which has brought prices down and made them viable alternatives to their pneumatic cousins. In fact, cordless impact wrenches have a tremendous advantage: mobility. Rather than being tied to a compressor with an air hose, these tools can easily go wherever they’re needed.
We tested a range of impact wrenches—from a heavy-duty, high-torque model down to a compact, medium-duty model—and subjected them all to the same challenges to identify their strengths and weaknesses. Read on for some buying advice, followed by our findings and reviews of the best impact wrenches we recommend.
Unlike cordless drill/drivers and impact drivers, which excel at drilling holes and driving screws, the cordless impact wrench is specially designed for tightening and loosening various hex-head bolts, nuts, and lag screws. It employs both rotational force and short-burst concussive blows for an unparalleled amount of power.
However, all that brute strength isn’t very useful if you can’t control the tool. Fortunately, cordless impact wrenches are extremely comfortable to use because the concussive blows smoothly transfer most of that high-energy torque directly to the fastener, not to your hand, wrist, or arm. As a result, the twisting motion—known as reactionary torque—that you feel when using an electric drill is virtually eliminated.
Torque measures the tool’s ability to drive in lag bolts or loosen stubborn nuts—the most important representation of power for an impact wrench. Most cordless drill/drivers produce about 50 foot-pounds of torque and the average impact driver delivers about 125 foot-pounds. By comparison, cordless impact wrenches can easily produce torque outputs of over 250 foot-pounds, which is more than enough muscle to power-drive the fattest lags and bust loose rusty, corroded nuts.
Generally speaking, the higher end (and pricier) cordless impact wrenches produce the greatest amount of torque. Torque output ranges from 225 foot pounds for sub-compact models up to 1,500 foot pounds of torque for the most powerful impact wrenches.
Impacts per minute (IPM) increase as revolutions per minute (RPM) increase. High RPM help drive nuts or bolts faster, while IPM kick in harder producing a faster rate of impacts as the resistance increases, thus transferring more torque to the drive head.
Impact wrenches produce massive amounts of speed and power, so being able to control it to avoid over tightening fasteners or spinning off lug nuts and sending them flying through your shop is key. Most impact wrenches have three or four speed settings that allow you to reduce the RPM and torque to lower levels to avoid these mishaps. Fancier impact wrenches have modes that automatically slow the wrench after it’s broken off a bolt to prevent spinning it off. Some have controls that allow you to dial in lower torques that simulate hand tightening or wrench tightening.
All things being equal, higher voltage gives you more power—but there are cases for lower voltage. With smaller batteries, 12-volt impact wrenches are more compact. This makes them good for smaller jobs, working overhead, or getting into tight spaces. Tools with 18 and 20 volts have less difference between them. Generally, 18-volt tools with advanced features and capabilities make them more versatile and easier to use.Amp hours (Ah) equals the number of amps that the battery discharges, continuously, for an hour. Think of amp hours like the volume of a gas tank—a bigger number equals more gas.
What are we talking about when we say size? The most common size impact wrenches are ½-inch drive models—those with a square anvil measuring ½ x ½-inch, that accepts ½-inch sockets. There are also smaller ⅜- and larger ¾-inch drive models, with the latter being for heavy vehicle maintenance, agricultural equipment, or other industrial uses.
Among half-inch impact wrenches, there are also tool body sizes—generally, full, compact, and sub-compact. If the tool isn’t labeled specifically compact or subcompact, you can assume it is a full-sized model. Full-size impacts have larger, longer tool heads, with beefier internals, and thus higher torque specs. They’re great for removing stubborn, rusted nuts and bolts. However, these bigger tools may not fit in the spaces where they are needed.
Compact and subcompact impact wrenches have shorter, less bulky, tool heads that fit into tight spaces better. Because they are smaller, they don’t have the high torque specs of the larger models, but they have more than enough for most assembly/disassembly tasks the average person might encounter. Their size and capability for common tasks makes compact impact wrenches incredibly versatile.
Every impact wrench on this list has been thoroughly vetted and evaluated by our test editors. We research the market, survey user reviews, speak with product managers and engineers, and use our own experience operating these tools to determine the best options.
We chose practical tasks that most people might need to accomplish with these impact wrenches. The first was removing and replacing lug nuts. Lug nuts removed were torqued to the recommended spec at 165 foot-pounds on a Ford F-250 Super Duty pickup truck—with compact wrenches, we removed them from a car torqued to a slightly lower spec of 150 foot-pounds. Standard sized wrenches were also used to remove, or break free, rusted nuts and bolts on an old piece of farm equipment.
While compact wrenches were used to remove and then replace new, 9/16-inch, grade eight bolts tightened to 200 foot-pounds. We evaluated them on performance, price, comfort, value, and versatility to determine the best impact drivers that meet the needs of a wide range of people.
