Milwaukee announced its M12 FUEL brushless tools at a media event in 2012. In 2013, we reviewed one of the earliest samples in the first print issue of the limited-run Pro Tool Reviews Magazine. These were the industry's first brushless 12V tools to hit the market and soon caught the attention of other manufacturers. Fast forward to 2017 and the company announced the release of products such as the updated Milwaukee M12 FUEL Impact Driver and the Milwaukee M12 Brushless Impact Drill. Both make welcome additions to the FUEL tool range, and both offer much-needed size reduction.
Is 12V about power or size?
Around the same time as the original brushless M12 impact driver and other tools were released, DeWalt released the DCF895B 20V Max brushless three-speed impact driver. Why is this important? Well, the 12V Milwaukee FUEL is less expensive and weighs only 1 lb 14 oz, but the 20V DeWalt DCF895B is a full 3/4 inch shorter!
Fast forward to today, and the new Milwaukee FUEL 1/4" Impact Driver (2553-20) has reduced its length to just 5.1 inches. It's finally shorter and 1.2 ounces lighter. It's been a long time coming, but Milwaukee seems to have found its special sauce of a mature combination of size and strength in its M12 bits and drivers.
See our articles on Drills vs Impact Drivers and Speed vs Torque in Drills and Impact Drivers
Milwaukee Fuel vs. First Generation Models
Let's get back to business. First, you should be wondering what has changed between the first generation tools and the newest Milwaukee M12 FUEL Impact Driver and M12 FUEL Impact Drill. The first generation of M12 tools performed well. The Milwaukee M12 Impact Drill came in third in our best 12V cordless drill roundup, and the M12 Impact Driver won our best 12V impact driver review comparison.
Milwaukee 2504-20 vs 2404-20 Hammer Drills: Size Matters

Never mind what Yoda said in The Empire Strikes Back, size does matter. This is very important when you choose a 12V tool to handle your daily work. For me, I've found that 12V tools can solve the same tasks that 18V NiCd tools did a decade ago (see our article 12V vs 18V tools). In this case, choosing a smaller size and weight can make the tool belt or bag more flexible. This certainly appeals to me, although I always have 18V tools handy when I need them.
Viewed side by side, the difference in length between the original Milwaukee M12 Hammer and the newer Milwaukee M12 Hammer is impressive:
Milwaukee shortened the length of the 2504-20 hammer drill considerably compared to the 2404-20. We measured a drop of 6-9/16 inches from 7-3/4 inches. Length is reduced by 1-3/16 inches! The way they did this was by redesigning the brushless motor assembly so they could embed the mode switch and clutch into the torsion ring. They also moved the fins to the rearmost side of the driver. All of these work together to save space. For weight, the Milwaukee dropped 2.4 ounces. That might not sound like much, but it matters in the long run, especially if you're working above eye level or doing repetitive tasks.
Updated Milwaukee M12 FUEL Impact Driver with 2453-20
Looking at the nose of the new Milwaukee 2553-20 impact driver, you can see how the impact mechanism and chuck are set further back towards the brushless motor. The fact that the Milwaukee did this while increasing torque by 100 inch-pounds is a testament to the apparent reliability of the design. The 0.9-inch reduction in length also allows the new FUEL impact driver to have a much smaller footprint. Thanks to Milwaukee's refocused mass, it still feels great in the hand.
While the space savings of the Milwaukee 2553-20 Impact Driver are remarkable, Milwaukee didn't stop there. They also added a 4-mode drive control that provides more flexibility in speed and torque control. In addition to its three speeds, the Milwaukee 2553-20 Impact Driver adds a self-tapping screw mode. In this mode, the tool will be driven at full RPM until the impact mechanism engages. The tool then slows down the RPM for better control as you drive the screw all the way in. It's designed for fastening to metal so you won't scrape your head off by driving too fast.
Milwaukee chose to keep the same bevel angle on their M12 FUEL impact driver and brushless FUEL impact drill. That means your grip doesn't change, and the balance we already felt good about is still excellent. The new M12 tools come with one or two Milwaukee RedLithium 2.0 or RedLithium 4.0 XC battery packs. Our 2-piece kit comes with one of each. The price for this kit (2598-22) is approximately $229.
build quality
As far as we can tell, the build quality of these new tools is excellent. For example, inside the stator of the Milwaukee 2553-20 and new 2504-20 hammer drills, you'll find a large 7-point star drive shaft that moves the gear assembly. All PCBAs (Printed Circuit Board Assemblies) are rigidly embedded in a glass-reinforced nylon body. This includes the main board and selector switch assembly. Having gone through more than one assembly line producing such products, the wiring assemblies and "trap" locations seem to be strategically placed to keep them from moving parts. The tool seems to be able to take some losses and keep going. Seven 16mm T-10 Torx screws are used for the case cover alone.

To give you a quick rundown of the specs, here are the differences between the new tools:
2404-20 | 2504-20 | 2453-20 | 2553-20 | |
---|---|---|---|---|
torque | 350 in-lbs | 350 in-lbs | 1,200 in-lbs | 1,300 in-lbs |
speed (low) | 0-450 | 0-450 | 0-1,200 | 0-1,300 |
speed (medium) | – – | – – | – – | 0-2,400 |
speed (high) | 0-1,700 | 0-1,700 | 0-2,650 | 0-3,300 |
BPM/IPM (Maximum) | 25,500 | 25,500 | 3,550 | 4,000 |
length | 7-3/4 inches | 6-9/16 inches | 6 inches | 5.1 inches |
Weight (without battery) | 2 lbs 8 oz | 2 lbs 5.6 oz | 1 lb 14 oz | 1 lb 12 oz |
How about the Milwaukee 2503-20 M12 FUEL Drill? Interestingly, the Milwaukee 2503-20 drill has the exact same specs and dimensions as the 2504-20 hammer drill — just without the hammering feature. Since the mode switch is integrated into the clutch mechanism, you no longer need to cut the length of the tool.
Milwaukee M12 FUEL Hammer Drill and Impact Driver Performance
Performance matters. Carry 12V tools with you as your "everyday carry", only those same tools will get the job done. These can. We put two M12 impact drills into our torque tester and measured the following:
- Milwaukee 2504-20 Maximum "Hard Stop" Torque: 27.1 ft-lbs (325.2 in-lbs)
- Milwaukee 2404-20 Maximum "Hard Stop" Torque: 26.0 ft-lbs (312.0 in-lbs)
While our numbers don't quite match up with Milwaukee's, here's the thing — our setup isn't the same as theirs. It is constantly changing as we build longer lasting and more powerful test equipment. Needless to say, both drills are within 4% and within 7% of what the manufacturer claims. Our next test tells us more.
Decoration and More Decoration
We have a children's playground that is in dire need of renovation. It has a rotting wooden beam and deck that you can practically put your feet through. Needless to say, it failed our safety standards. Instead of replacing the trim with 5/4 board, we went straight to the pressure treated 2×6 board. Grabbing a newer Milwaukee M12 impact driver and some deck screws, we got to work. Not only does it do a great job of removing old decks, but it also snaps in over a pound of new 3" deck screws. I like the new M12 because it has better ergonomics. It's well balanced like the previous model, but the space savings of the Milwaukee 2553-20 make it easier to fit into tight spots.

If I had any complaints about the newly upgraded Milwaukee M12 FUEL Impact Driver and Hammer Drill it would have to be about the belt clip. While the clip is great for carrying your tools in your pocket, it does get in the way during overuse. As a right-hander, I tend to keep my left hand on the back of the tool. This puts the meat under my thumb right on top of the belt clip. It gets pretty sore after a few uses. The solution (if this bothers you) is to reverse or remove the belt clip.
The new combination chuck and clutch on the Milwaukee 2504-20 hammer drill allows easy rotation and quick entry and exit of hammering mode as needed. I like the separate hammer mode dial on the 2404-20. Whenever possible, I try to reduce moving parts. The new drill bits are easy to clip on and use.

in conclusion
The conclusion can only be that the newly updated Milwaukee M12 FUEL impact driver and hammer drill is superior to the old model in almost every way. While the power seems relatively unchanged, the added ergonomics and features make for a huge upgrade. It's been about five years since these tools debuted, so early adopters of the M12, for one reason or another, may be back on the market. Milwaukee re-entered the 12V game with some very competitive tools. Coupled with their extensive M12 platform, choosing between the 2504-20 or 2553-20 becomes easy. These tools certainly come with our recommendations (for the best value, choose the combo kit).
Pricing and options:
- Milwaukee M12 FUEL Impact Driver Bare Tool (2553-20) – $99.99
- M12 FUEL Impact Driver Kit (2553-22) – $169
- Milwaukee M12 FUEL Hammer Drill Bare Tool (2504-20) – $129
- M12 FUEL Hammer Drill Kit (2504-21) – $149
- Milwaukee M12 FUEL 2 Tool Combo Kit (Impact Drill + Impact Driver 2598-22) – $229