Milwaukee M12 Fuel Circular Saw Gen 2 Model 2521

The Milwaukee M12 Fuel 5 3/8-Inch Circular Saw Redefines Compact Power

Milwaukee is launching an updated M12 Fuel 5 3/8-inch circular saw with a couple of real “wow” factors built in. I actually did a double-take when I saw Milwaukee refer to the 2521 as just the second-generation model, considering I wrote about the first-generation 2530 way back in 2015.

It’s hard to believe in such a fast-changing world that a cordless saw—especially a 12V model—could have a 9-year run. For those of us who have used that saw, it’s not such a surprise. That said, battery and motor technology have improved tremendously over that time, so I’ll share what to look for in the new model and help you decide if you should upgrade.

Watch our video version of this review:

Milwaukee M12 Fuel Circular Saw Performance

Cutting Power

If you’re new to the 5 3/8-inch circular saw class, they’re the most compact models we use, but don’t accuse them of being DIY products. They still have enough cutting capacity to handle 2x lumber and sheet goods. With a more compact size and lighter weight, they’re a popular option for tradesmen who don’t need higher capacity or extreme runtime, such as remodelers.

The first area of improvement is in the saw’s performance. For starters, the blade speed jumps by 250 RPM, topping out at 3850 RPM. Additionally, it has a max cut depth of 1-1/2 inches and can bevel up to 50 degrees.

In addition to the higher speed, you can also expect an increase in power. Between the latest M12 Fuel PowerState brushless motor and the relatively recent expansion of M12 5.0Ah High Output batteries, the saw can ask for more power and the battery is capable of delivering it. During our testing, it handled cross, miter, bevel, and compound miter cuts with relative ease. For such a compact saw, the Milwaukee 2521 really does pack a punch.

Visibility

Overall, I’ve been happy with the performance level of this saw, but there is one area where I think it falls short, and that’s in the area of blade visibility. I’m right-handed, and since this is a blade-left saw, the sight line to the blade is slightly obscured by the upper blade guard while cutting at 90-degrees. At 45-degrees, the sight line is much clearer, but it does take a little practice to make accurate cuts. Thankfully, there are notches on the front of the shoe to help with proper alignment.

Milwaukee M12 Fuel Circular Saw Design Notes

Size and Weight

The other big deal is a significant reduction in weight. The first-generation 2530 weighed 5.3 pounds. The new 2521 drops all the way down to 4.7 pounds as a bare tool, and a mere 5.6 pounds with the kitted 5.0Ah battery. Losing over half a pound on a compact tool makes it even easier to work with.

If that isn’t enough, this second-generation saw is also even more compact. At 10.9 inches long, it’s nearly 1.5 inches shorter than the previous model 2530. This compact profile makes it very easy to maneuver, and even allows you to cut overhead and in tight spaces where a full-size saw simply wouldn’t fit.

Milwaukee M12 Fuel Circular Saw 2530 vs 2521 Quick Comparison

Other Helpful Features

Looking at this saw’s features, it’s clear to me that the 2521 is a true workhorse. It features a folding rafter hook, an LED work light, a dust blower, and it’s compatible with an edge guide for longer rip cuts. It also comes with a removable dust nozzle and a battery life indicator on the side of the handle.

Milwaukee M12 Fuel Circular Saw Price

As a bare tool, the saw is $159. The kit includes a 5.0Ah High Output battery and is $259. Both options are only $10 more than the previous version, meaning these impressive upgrades aren’t going to cost much more to take advantage of. The tool is backed by a 5-year warranty.

The Bottom Line

With the Milwaukee M12 Fuel 5 3/8-inch circular saw, the design team took a very good saw and made it even better. Its performance bump along with a solid design and compact size makes this saw a winner in my book. While there are some limitations on cut capacity and visibility, I think the Pro market and serious DIYers well reap some major benefits!

Specifications

• Model: Milwaukee 2521
• Power Source: M12 RedLithium Battery Pack (High Output recommended)
• Blade Size: 5-3/8 or 5-1/2 inches
• Arbor: 10mm
• No Load Speed: 3850 RPM
• Bare Weight: 4.7 lbs (bare tool), 5.6 lbs (with 5.0Ah battery)
• Warranty: 5 years

Is There a M12 Fuel 6 1/2-inch Circular Saw in the Future?

With the higher performance, I wondered if we might see an M12 Fuel 6 1/2-inch circular saw at Pipeline in the next year or two. It’s an interesting question, and I think the answer is… not yet.

With the improvements in the battery and motor, I believe the M12 system already has the available power to make a 6 1/2-inch saw work well. However, runtime is still an issue. The 5.0Ah High Output battery has the same capacity as an M18 3.0Ah battery—54 watt-hours. While you certainly could get some work done, most Pros rely on low-capacity batteries as a backup option rather than a primary one for circular saws.

Then there’s the payoff. By moving to a 6 1/2-inch blade, you’re gaining the cut capacity for 45° cuts in 2x lumber which the 5 3/8-inch blade can’t complete. While that would be a convenient upgrade, it’s a tougher cut, further reducing the number of cuts you can make on a charge.

I think we’ll need to see another big jump in brushless motor efficiency to make the runtime more relevant before we see an M12 Fuel 6 1/2-inch model. Never say never, though. Milwaukee’s design teams are typically thinking several years ahead on product development, and they frequently surprise us with what they’re ready to launch.