DeWalt comes in with the most nut-busting power at 1,200 ft. lbs of maximum breakaway power, along with 700 ft. lbs. of maximum torque. That makes it the most powerful cordless impact wrench currently on the market. A little heavier than the Matco below, it comes in at 7.2 pounds. That's still rather light and the 8-13/16" overall length helps get it into tight places. This tool is built with a brushless motor, reducing maintenance by eliminating the need to replace the brushes. The anvil on this tool is equipped with a detent pin, the only thing I don't really like; but lots of other people like them, so I won't hold that against it. Speed is variable, with three ranges including 0-400, 0-1,200, and 0-1,900 RPM. It also includes a LED light with a 20 second delay to increase visibility while you are working.
Milwaukee has several excellent cordless impact wrenches to choose from. I've picked this one as their best, mostly for the power it offers. Like the Matco below, it has 700 ft. lbs. of constant torque (in mode 2), and 1,100 ft. lbs. for busting nuts loose. The tool is variable speed with an electric brake. That adds a little bit of safety to using the tool. It also has a LED light to light up the work area; this is a nice feature finding its way onto more and more power tools. The anvil on this tool uses a friction ring to keep the sockets in place and while some people prefer a detent, I find a friction ring easier to work with. You can buy the tool as a bare tool or in a kit with two 4.0 Ah, 18 volt batteries, and a multi-voltage charger.
Matco is a professional tool company, servicing mechanics, like Snap-On does. However, their tools don't usually have as high a price as Snap-On's do. I won't get into a discussion about which is better, although I did choose their 1/2" cordless impact over Snap-On's offering. That's mostly for the high amount of power it offers. This impact gives you 780 ft. lbs. of reverse torque, with burst of 1,100 ft. lbs. of torque for busting nuts loose. That's ties for the most power than I've found in any cordless impact. The power train is all metal to handle that much torque. At 6.8 pounds, that's an incredible power to weight ratio. It comes with two 3.0 Ah Li-Ion batteries, a charger, and a storage case.
Snap-On CT6850 Cordless 1/2" Drive Impact Wrench
Snap-On offers a huge selection of cordless impact wrenches to choose from which made it difficult to pick out a best one. However, I like this particular model for the combination of features it offers. The torque on this tool is lower than the ones I've already mentioned, providing 400 ft. lbs. But the bolt break-away torque is 620 ft. lbs. That's still enough for lots of work, so if you don't need the high torque of the others, you may want to consider the Snap-On for their quality reputation. This one also uses a friction ring on the anvil, rather than a ball detent. It's 7.6 pounds, measures 9.95" in overall length, and comes with Ni-Cad batteries rather than Li-Ion, so the batteries have a 2.5 Ah capacity. The kit comes with two batteries and the charger.
Makita offers this unit as either a bare tool or a kit but I've selected the bare tool, simply because I have other Makita tools, so I already have the batteries and charger. This one produces 325 ft. lbs. of max torque. The manufacturer doesn't list a breakaway torque, so I have to assume that there isn't one. One thing I like about this tool is that the handle is shock absorbent. This not only protects your wrists, but it also reduces fatigue on the tool thereby reducing chances that the handle, which is the battery compartment on all these tools, will break. This tool also is equipped with an LED worklight which illuminates your work area. It uses Makita's standard 18V LTX Li-Ion batteries.
DeWalt's corded impact wrench comes in real close to the following two models, in the power department, at 345 ft. lbs. of torque. No load speed is 2100 RPM and it delivers 2700 IMP of impact power, making it very comparable to the other two. The manufacturer's web page states that this one has ball bearing construction which the others on our list don't mention, giving this tool the number one slot. However, this one does not have a work light or the power indicator light; while those are minor features, they do come in as a tie breaker. The anvil on this tool has a detent for holding the sockets in place, rather than the friction ring the others had. I prefer the friction ring, but some prefer the detent. The power switch is a rocker for ease of use and the handle is nicely padded for comfort.
Kobalt Model #6904, 1/2" Corded Impact Wrench
Kobalt tools are a brand of Lowe's Home Improvement Centers, manufactured to compete with Craftsman. I have a few of their tools and from what I've seen of them, they are well built, rugged tools that are intended to last. We can see that from the five year "hassle-free" guarantee that they put on this tool. At 350 ft. lbs. of torque, this one ties for first place in overall power. The 8 amp motor gives you plenty to work with, running at 2100 RPM and 2700 IPM of impact power. The trigger is a toggle switch, making it easy to change directions, when you need to. It also includes a live wire indicator for safety and comes with 7 deep well impact sockets. Sockets are held in place by a "bull-nose" friction ring.
Craftsman #6903, 1/2" Corded Impact Wrench
Craftsman's 1/2" corded impact wrench has specification close enough to the Kobalt that one could almost wonder if they came out of the same factory. However, they are different enough in appearance that it's doubtful that's the case. This one also provides 350 ft. lbs. of torque, running at 2100 RPM and 2700 IMP of impact power. That makes the two tools comparable. However, the Craftsman doesn't have the five year warranty of the Kobalt, which is why I gave the number one slot to them.
This one also has a toggle operated trigger, giving you excellent control over tool operation. They add a LED work light located at the base of the handle so the tool's nose doesn't put a shadow right where you need to see. It also has the green power indicator light at the base of the handle which Craftsman has been putting on a lot of their power tools. Lastly, a "bull-nose" friction ring holds the sockets in place.
Milwaukee 1/2" Electric Impact Wrench with Rocker Switch
My initial inclination was to give Milwaukee the number one spot on this list, just due to their quality and ruggedness. Impact wrenches receive a lot of hard usage and I have a lot of confidence in Milwaukee's tools to handle that, but the specs pushed it out of that top spot. While this is an excellent impact wrench, it's not quite as powerful as the one's we've already looked at. This wrench is rated at 300 ft. lbs. It's motor runs at 1800 RPM and the impact hammer provides 2600 IPM. However, I have to say that from my experience with Milwaukee's tools, I'd say it might still outperform one of the others. At 6.0 pounds, it appears to be lighter than the others (although they don't all give their weight). The anvil on this one uses a friction ring retention system and it has a rocker switch trigger.
I'm a big Makita fan, but I have to admit that the other tools on this list actually beat out Makita's impact wrench this time around. However, this tool has some nice features that are important to see. First of all, the tool is producing 258 ft. lbs. of torque, running at a variable speed of 0 - 2000 RPM. The other tools were not variable speed, so if you need a tool which you can use for a variety of types of equipment, this one might actually be a better choice. At 2000 RPM, it also provides 2000 IMP of impact power, as well as running off of much less electrical power than the competition, needing only 3.5 amps of power. If you're running off an already overburdened generator or trying to use a voltage inverter for power, that's an important consideration. Finally, the tool is built with ball bearings for the motor, to ensure long life and the brushes are externally accessible for easier maintenance.
This is not the most powerful impact wrench out there, but for the home mechanic and do-it-yourselfer, it just very well might be the most useful one. The really short length of this tool at 4.4 inches and light weight at 2.86 pounds, make it ideal for working on a wide number of projects. Even so, it provides 450 ft. lbs. of maximum torque, from a motor running at 9,000 RPM. That means it's going to be working faster than most other impacts out there. The forward/reverse control is located right at the trigger where they are easy to get to, as well as the power setting to access the three different levels of power in both forward and reverse. A steel front cover and aluminum body make it durable so that it will provide years of useful service.
Snap-on MG725L, 1/2" Heavy Duty Air impact Wrench with Magnesium Housing
Snap-on tools are widely considered the finest mechanics tools made. This heavy-duty impact wrench shows that, as it is one of the most powerful 1/2" impacts I've seen. Providing an outstanding 1190 ft. lbs. of breakaway torque, this impact wrench is ready to take apart anything you set it to. Working torque is 810 fl. lbs. so even when you're not in maximum working mode, you still have tons of power. The case is magnesium for strength and weight, allowing Snap-on to keep the tool's weight down to five pounds. While that is heavier than the Chicago Pneumatic tool in first place, it is also a larger tool, providing considerably more power. The motor runs at 9,800 RPM and provides 1,270 BPM of impact power from its twin hammers. Sockets are held in place by a friction ring for quick tool changes. An anvil brake stops the anvil from turning when the trigger is released, preventing the tool from accidentally throwing sockets and nuts.
Ingersoll Rand's 2135TiMAX provides an impressive power to weight ratio, in a 3.95 pound package. Even though it's light, this impact wrench provides 780 ft. lbs. of torque when needed. When it's time to bust the nuts loose, that increases to 1100 ft. lbs. Twin hammers make fasteners come off quicker by increasing the number of blows provided. A feather touch trigger helps to provide excellent control over the tool and how much power it is providing. Direction change is accomplished with the same hand that's holding the tool, meaning you can do anything one-handed.
Chicago Pneumatic has confronted the biggest problem with impact wrenches in this tool. When used for assembly, impact wrenches tend to provide too much power, causing you to tighten fasteners beyond their specified torque. This wrench limits the torque on tightening, allowing you only enough to snug the fasteners. You have to come back with a torque wrench to finalize. In a forward direction, the tool only provides 60 ft. lbs. of torque; enough to snug down any fastener, but when used for disassembly, it has 925 ft. lbs. of power at 8200 RPM. That's enough to break just about anything loose. The reverse switch is located on the back of the housing, where it is easily accessible to the thumb of the hand which is holding the tool. A full teasing trigger allows for smooth control at any power.
If you're concerned about a tool breaking or the casing becoming deformed, this NitroCat is for you. The case on this tool is made of a Kevlar composite, the same material used for a bullet-proof vest. The Kevlar provides incredible strength to the composite case, ensuring that the tool won't break even under extreme situations. It also provides 1295 ft. lbs. of maximum loosening torque, even beating out the Snap-on that I thought was the most powerful. Coupled with 950 BPM of impact power through its unique twin-clutch mechanism, there's not much that this tool won't break loose. On the tightening side, it provides 200-900 ft. lbs of torque. The Kevlar composite case also helps keep the weight down to 4.5 pounds for operator comfort.