These Cordless Impact Wrenches Allow For More Mobility

Historically, impact wrenches were predominantly pneumatic, or air powered, which left them squarely in the domain of professional mechanics. To run a typical ½-inch pneumatic impact wrench, you usually need an air compressor putting out close to 100 PSI—a significant investment.

The good news is that cordless, 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. Not being tied to a compressor with an air hose, these tools can easily go wherever they’re needed.

We called in 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.

What You Need to Know About Impact Wrenches

How They Work
Unlike cordless drill/drivers and impact drivers, which excel at drilling holes and driving screws, the impact wrench is specially designed for tightening and loosening various hex-head bolts, nuts, and lag screws. It employs both rotational force (torque) and short-burst concussive blows (impacts) to deliver an unparalleled amount of power. For example, 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.

However, all that brute strength isn’t very useful if you can’t control the tool. Fortunately, 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.Batteries: Volts
All things being equal, higher voltage will give 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.
Batteries: Amp Hours (Ah)
Ah (amp hours) equals the number of amps that the battery will discharge, continuously, for an hour. Think of amp hours, like the volume of a gas tank—a bigger number equals more gas.
IPM/RPM
IPM (impacts per minute) increase as RPM (revolutions per minute) increase. And high RPMs help drive nuts or bolts faster, while IPMs kick in harder as the resistance increases.

How We Tested These Impact Wrenches

Every impact driver 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 torqued to the recommended spec at 165 foot-pounds on a Ford F-250 Super Duty pickup truck. The second task was to remove, or break free, rusted nuts and bolts on an old piece of farm equipment. We evaluated them on performance, price, comfort, value, and versatility, to determine the best impact drivers that will meet the needs of a wide range of people.